The covert nonnative-like phenomena is a new achievement developed out of the study of nonnative-like phenomena in China in recent years.It refers to the tendency that the second language（L2）learners frequently using the grammatically correct but first language（L1）loaded L2 expressions during their learning.This paper,which approaches the causes of the phenomena from the angles of frequency,L2 linguistic levels and L1 language interference,illuminates that the word frequency factor has an effect on the words mental representation which in turns causing the expressing difference between the native and L2 learners and that the immaturity of L2 system and the interference of L1 as a whole result in L1 loaded L2 expressions.