The invention discloses a tumor cell detecting method, and belongs to the technical field of tumor cytology. The detecting method comprises the following steps of applying alpha fetoprotein with enzyme labeling or alpha fetoprotein heteroplasmon to combine with alpha fetoprotein acceptor heteroplasmon expressed by tumor cell; through the chromogenic reaction between substrate and enzyme, dyeing the tumor cell, and thereby distinguishing the tumor cell and the normal cell. The tumor cell detecting method can specially identify the tumor cell; the method overcomes the shortcomings of the traditional dyeing method, and is applicable to various tissue specimens or cell specimens; therefore, the method has very abroad application prospect.