这是肯定句,need 应该是实意动词,
当need 作实意动词时,后面跟动词不定式 need to do sth
need 作情态动词时,常用于疑问句和否定句,
后面跟动词原形.
因此正确的句子应该是：
I need to go to Shanghai next week to attend a meeting.