The R matrix approximation is used to compute the excitation collision strength of electron impact on Lilike C with the configuration interaction wavefunctions, in which the configuration inte ractions of an innershell electron excitation are included. For transition 1s ２２s２S１s１２p２Po,the result in this paper is a litt le smaller than that of the close coupling approximation and a little larger than that of CoulombBornexchange approximation，and accords with that of the experiment except that nearer excita tion threshold.