Abstract: Based on the fact that Schroeter deconvolution needs the initial reservoir pressure as a known condition，and that the reservoir response functions are much sensitive to the exactness of this value，a new method is proposed，based on Levitan method，to deconvolve without the knowledge of true initial reservoir pressure，which is obtained by convolution of rate and unit-rate pressure response from equilibrium time to reference time during deconvolution.Detailed comparisons between the results from this method and those from Levitan method involving true initial reservoir pressure show that it gives correct deconvolution results without initial reservoir pressure，and that the selection of reference time has no impacts on the final results.Moreover，it can deconvolve not only all test data，but also part of individual ones.

Key words: well test, initial reservoir pressure, sensitivity, reference time, superposition, deconvolution