Dachang is a well known old Sn polymetallic mine and more successive mineral resources is ur- gently needed. TEM and well logging method etc. have been applied to Yangjiaojian-Laoshan area with good geophysical exploration results. The methods resolve low resistance and high polarization of mud- stone and disturbance of pyrrhotite resulted from the syn-sedimentary pyrite and open a new road for anti - strong disturbance.