select DISTINCT VOD_VodOrder.* from VOD_VodOrder join 
VOD_VodOrderItem on VOD_VodOrder.Id = VOD_VodOrderItem.ParentId where .....

var dd=from t1 in VodOrders join t2 in VodItems on t1.Id equals t2.ParentId where...
select ... ;
dd = dd.Distinct();

------解决方案--------------------
给你一个参考吧
           var varQnum = from pRow in dttRuleData.AsEnumerable()
                         where pRow.Field<string>("NODE_TYPE") == GetLinqQuery(FlowRule.C_TYPE_N)
                         group pRow by pRow.Field<string>("NODE_VALUE")
                             into g
                             select new
                            {
                                g.Key,
                                nodeCode = g.Count()
                            };

------解决方案--------------------

var result =  r1 from vod_vodorder
                 join r2 from vod_vodorderitem  on r1.id eauals r2.id
                where r1.fileld<string >("creatorid") = 变量 &&
		r1.fileld<int>("iscompleted") = 变量 &&  
		r1.fileld<string>("remarks") = 变量 &&  
		r2.fileld<int>("moveid") = 变量  
	select new  
{
id = r1.files<string>("id"),
creatorid = r1.fileld<int>("creatorid") ,
iscompleted =r1.fileld<int>("iscompleted"),
remarks = r1.fileld<int>("remarks"),
createdate = r1.fileld<datetime>("createdate")
}.distince().tolist();