We study the $f(R,T)$ cosmological models under self-similarity hypothesis. determine exact form that each physical and geometrical quantity may take in order Field Equations (FE) admit self-similar solutions through matter collineation approach. two models: case$\ f(R,T)=f_{1}(R)+f_{2}(T)$ case $f(R,T)=f_{1}(R)+f_{2} (R)f_{3}(T)$. In case, we state general theorems which completely of unknown ...