While negative transfer of the native linguistic knowledge inSLA is closely studied, other aspects of the learner’s nativeknowledge have been ignored. The following is an investigationand study in this respect, revealing that negative transfer not on-ly happens in the aspect of the learner’s native linguistic knowl-edge such as that of the native grammatical rules and lexical con-ception, but also happens in aspects of cultural conventions andthinking patterns. It is also found that negative transfer of lin-guistic knowledge decreases with the learner’s progress in studywhile the other two aspects have no obvious decrease. With Level3 as a control group, this paper confirmed the effectiveness andnecessity in offering classes dealing with the other two aspects ofnegative transfer.