On the basis of long term research on filling support mechanism in Jingchuan Nickel Mine, a constitutive equation on coincidental deformation among wallrock, orebody and fill was established by using viscoelastop-lastic theory and increment calculation method with the equation, the problem of wallrock stability has been solved satisfactorily. It is shown that the predicted results were tallied with actually measured wallrock displacement. Taking these constitutive equations as a theoretical basis, a large scale of mining production has been conducted by using under cut-and-fill cement filling in No.1 orebody of Jingchuan's No.2 mining area , resulting in remarkable profits.