This paper presents a new computation of matrix inversion. It gives out not only the programs but also applied examples.The resolution of A is A=LU, then A~(-I)=L~(-I)+(I-U) A~(-I),or, A~(-I)=U~(-1)+A~(-I)(I-L). when A is positive definite, the resolution of A is A=LDL~T, and then we have A~(-I)=D~(-I)L~(-I)+(I-L~T)A~(-1), or, A~(-I)=L~(-T)D~(-1)+A~(-1)A~(-1)(I-L~T). Compared with the litererature references[1], not only is the work load reduced, but also the stability of the computation is increased because of the reduction of division operation.