Toxic Chinese materia medica has been highly valued by its specialized and effective effects， but its safe application has become an urgent clinical problem to be solved. Compatibility for toxic attenuation is an important method for the rational clinical application of toxic Chinese materia medica as well as the promotion of its therapeutic advantages. The theory of “heterogeneous medicinals mutual restriction” elaborated in this article has been formed through long-term clinical practice and cognition， and refinement of clinical experience， which means that the nature partiality of toxic Chinese materia medica can be adjusted， and the toxicity can be suppressed through reasonable combination with herbal medicinalsof different properties， flavors， and effects. This theory covers the modes of compatibility for toxicity attenuation and the interaction relationships， like the restriction of medicinals with different properties and flavors， restriction of medicinals with different effects， and inhibiting toxins by reinforcing healthy qi. The opposite and complementary effects of various medicinals combinations are an extension of the connotations of this theory， and the principles can be explained from material basis and mechanism of action. Under the guidance of this theory， it is possible to optimize the compound prescription strategies of toxic Chinese materia medica， and provide new strategies for the clinical combinations of toxic Chinese materia medica， thereby achieving the reduction of toxicity and enhancement of effectiveness of the compound formulas.