<style> 
    html { 
        -webkit-filter: grayscale(100%); 
        -moz-filter: grayscale(100%); 
        -ms-filter: grayscale(100%); 
        -o-filter: grayscale(100%); 
        filter:progid:DXImageTransform.Microsoft.BasicImage(grayscale=1);  
        _filter:none; 
    } 
</style>

<style>
html{filter:progid:DXImageTransform.Microsoft.BasicImage(grayscale=1);}
</style>

<style>
html {filter: grayscale(1);}
</style>

#BODY {   
filter:progid:DXImageTransform.Microsoft.BasicImage(grayscale=1);   
}

最后一个其实和第一个一模一样

<style type="text/css">
html, body {
    filter: 
progid:DXImageTransform.Microsoft.BasicImage(grayscale=1);
    -webkit-filter: grayscale(100%);
    -moz-filter: grayscale(100%);
    -ms-filter: grayscale(100%);
    -o-filter: grayscale(100%);
    filter: grayscale(100%);
    filter: gray;
}
</style>