var h3 = $('h3');
var text = h3.text().split(' ');
 
for( var i = 1,len = text.length; i < len; i=i+2 ) {
    text[i] = '<span>' + text[i] + '</span>';
}
h3.html(text.join(' '));

http://jsfiddle.net/H5zzq/

要么

var h3 = $('h3');
var text = h3.text().split(' ');
 
$.each(text,function(i,val) {
    if( i % 2) {
        text[i] = '<span>' + val + '</span>';
    }
});
h3.html(text.join(' '));

http://jsfiddle.net/H5zzq/1

处理&正如您在评论中所要求的那样,我创建了一个偏移量变量,只要遇到一个变量就会增加.

var h3 = $('h3');
var text = h3.text().split(' ');
var offset = 0;
 
for( var i = 1,len = text.length; i < len; i++ ) {
    if( text[i] === '&' ) {
        offset++;
    } else if( (i-offset) % 2 ) {
        text[i] = '<span>' + text[i] + '</span>';
    }
}
h3.html(text.join(' '));

http://jsfiddle.net/H5zzq/3