The magnetic properties of the mixed ferro-ferrimagnetic compounds with (A a B b C c ) y D, in which A, B, C and D are four different magnetic ions and form four different sublattices, are studied by using the Ising model. And the Ising model was dealt with standard mean-field approximation. The regions of concentration in which two compensation points or one compensation point exit are given in c-a, b-c and a-b planes. The phase diagrams of the transition temperature T c and compensation temperature T c o m p are obtained. The temperature dependences of the magnetization are also investigated. Some of the result can be used to explain the experimental work of the molecule-based ferro-ferrimagnet (Ni I I a Mn I I b Fe I I c ) 1 . 5 [Cr I I I (CN) 6 ].zH 2 O.