Abstract: The total compensation method (TCM) provides an effective approach to the solution of the composite inversion problem with incomplete input information. But the algorithm neglects the difference of certainty between known and unknown input when estimating the parameters, and therefore causes instability and slow parameter convergence. In this paper, an updated total compensation method (UTCM) based on weighted least square criterion is proposed, which makes full use of the incomplete input information. The new algorithm is improved significantly in both theory and convergence. The efficiency and accuracy of the new algorithm is investigated numerically and the results are compared with those obtained using TCM. It is shown that the computing time needed for UTCM is 10 times less than that for TCM.