Abstract: The ranges and radial velocities of targets are interesting parameters in the active sonar, which can't be observed directly but rather estimated. Firstly, by making use of the delay-Doppler model of multi-targets in waveguide multipath environment, one finds that sample cross-ambiguity function is a two-dimensional (2D) convolution of the autoambiguity function of the transmitted signal with the generalized target reflectivity density, which is a 2D convolution of the spread function of channel with the reflectivity density as well. Secondly, from the perspective of information theory, an iterative deconvolution algorithm named R-L (Richardson-Lucy) is derived based on minimum Csiszar discrimination criterion. Finally, the blurs caused by both of the transmitted signal and channel are removed by 2D deconvolution of the expectation of sample cross-ambiguity function, 2D image and then parameters of time-delay and Doppler is estimated sequentially. Results of both numerical simulation and sea experimental data processing verify the feasibility and effectiveness of R-L deconvolution algorithm with improving the resolution and accuracy of the estimations, when compared to the classical match filtering and Wiener filtering.