laravel ajax 500 TokenMismatchException

<meta name="_token" content="{{csrf_token()}}">
<script>
$(function(){
$.ajaxSetup({
headers: {
'X-CSRF-TOKEN': $('meta[name="_token"]').attr('content')
}
});
});
</script>
Route::post('/auth/ajax', 'AuthController@ajax');

$.post('/auth/ajax',param,function(re){
if(re.code=='100'){
layer.msg('你已经有账号了,请直接登录');
setTimeout(function(){window.location.href='/login';},1000)
}else{
check_email=true;
$(".input").show();
btn.html('注册');
}
})

TokenMismatchException in VerifyCsrfToken.php line 68:

post 提交的时候 $request->session()->token(); 和 我传上去的token 不同

各位大神有办法解决没？TokenMismatchException