Foreigners often make some strange mistakes in Chinese when they study the most difficult language--- ---Chinese. We try to analyze typical sentences to correct these errors.

          Zuótiān wǒmen jiàn ɡuò miàn, wǒ zhīdào tā.
False: 昨天我们见过面,我知道他。
          Zuótiān wǒmen jiàn ɡuò miàn, wǒ rènshí tā.
True: 昨天我们见过面,我认识他。

在汉语中“知道”可以表示头脑中对事实、情况已经认识它的存在;“认识”指跟人的相识并来往。既然“昨天我们见过面”,应删去“知道”,改为“认识”。
知道 means to be conscious of a fact. 认识 means to be acquainted with somebody. 认识 should be used instead of 知道.