HTML:

<div id="loader-wrapper">
    <div id="loader"></div>
    <div class="loader-section section-left"></div>
    <div class="loader-section section-right"></div>
    <div class="load_title">
        <span>Loading...</span>
    </div>
</div>

CSS:

#loader-wrapper {
    position:fixed;
    top:0;
    left:0;
    width:100%;
    height:100%;
    z-index:9999999;
}
#loader {
    display:block;
    position:relative;
    left:50%;
    top:50%;
    width:150px;
    height:150px;
    margin:-75px 0 0 -75px;
    border-radius:50%;
    border:3px solid transparent;
    border-top-color:#FFF;
    -webkit-animation:spin 2s linear infinite;
    -ms-animation:spin 2s linear infinite;
    -moz-animation:spin 2s linear infinite;
    -o-animation:spin 2s linear infinite;
    animation:spin 2s linear infinite;
    z-index:1001;
}
#loader:before {
    content:"";
    position:absolute;
    top:5px;
    left:5px;
    right:5px;
    bottom:5px;
    border-radius:50%;
    border:3px solid transparent;
    border-top-color:#FFF;
    -webkit-animation:spin 3s linear infinite;
    -moz-animation:spin 3s linear infinite;
    -o-animation:spin 3s linear infinite;
    -ms-animation:spin 3s linear infinite;
    animation:spin 3s linear infinite;
}
#loader:after {
    content:"";
    position:absolute;
    top:15px;
    left:15px;
    right:15px;
    bottom:15px;
    border-radius:50%;
    border:3px solid transparent;
    border-top-color:#FFF;
    -moz-animation:spin 1.5s linear infinite;
    -o-animation:spin 1.5s linear infinite;
    -ms-animation:spin 1.5s linear infinite;
    -webkit-animation:spin 1.5s linear infinite;
    animation:spin 1.5s linear infinite;
}
@-webkit-keyframes spin {
    0% {
    -webkit-transform:rotate(0deg);
    -ms-transform:rotate(0deg);
    transform:rotate(0deg);
}
100% {
    -webkit-transform:rotate(360deg);
    -ms-transform:rotate(360deg);
    transform:rotate(360deg);
}
}@keyframes spin {
    0% {
    -webkit-transform:rotate(0deg);
    -ms-transform:rotate(0deg);
    transform:rotate(0deg);
}
100% {
    -webkit-transform:rotate(360deg);
    -ms-transform:rotate(360deg);
    transform:rotate(360deg);
}
}#loader-wrapper .loader-section {
    position:fixed;
    top:0;
    width:51%;
    height:100%;
    background:#20409a;
    z-index:1000;
    -webkit-transform:translateX(0);
    -ms-transform:translateX(0);
    transform:translateX(0);
}
#loader-wrapper .loader-section.section-left {
    left:0;
}
#loader-wrapper .loader-section.section-right {
    right:0;
}
.loaded #loader-wrapper .loader-section.section-left {
    -webkit-transform:translateX(-100%);
    -ms-transform:translateX(-100%);
    transform:translateX(-100%);
    -webkit-transition:all 0.7s 0.3s cubic-bezier(0.645,0.045,0.355,1.000);
    transition:all 0.7s 0.3s cubic-bezier(0.645,0.045,0.355,1.000);
}
.loaded #loader-wrapper .loader-section.section-right {
    -webkit-transform:translateX(100%);
    -ms-transform:translateX(100%);
    transform:translateX(100%);
    -webkit-transition:all 0.7s 0.3s cubic-bezier(0.645,0.045,0.355,1.000);
    transition:all 0.7s 0.3s cubic-bezier(0.645,0.045,0.355,1.000);
}
.loaded #loader {
    opacity:0;
    -webkit-transition:all 0.3s ease-out;
    transition:all 0.3s ease-out;
}
.loaded #loader-wrapper {
    visibility:hidden;
    -webkit-transform:translateY(-100%);
    -ms-transform:translateY(-100%);
    transform:translateY(-100%);
    -webkit-transition:all 0.3s 1s ease-out;
    transition:all 0.3s 1s ease-out;
}
.no-js #loader-wrapper {
    display:none;
}
.no-js h1 {
    color:#222222;
}
#loader-wrapper .load_title {
    font-family:'Open Sans';
    color:#FFF;
    font-size:19px;
    width:100%;
    text-align:center;
    z-index:9999999999999;
    position:absolute;
    top:60%;
    opacity:1;
    line-height:30px;
}
#loader-wrapper .load_title span {
    font-weight:normal;
    font-style:italic;
    font-size:13px;
    color:#FFF;
    opacity:0.5;
}

JS:

加载使用

$(window).load(function () {
    $('body').addClass('loaded');
    $('#loader-wrapper .load_title').remove();
});

效果: