The invention discloses a super-short baseline water sound 
positioning system based on maximum likelihood 
estimation and a positioning 
algorithm, which solves the technical problem that the long-distance positioning accuracy of the super short baseline 
positioning system is low. The super-short baseline water sound 
positioning system consists of an under-water responder and a sound reception basic matrix, wherein the under water responder is capable of generating and emitting ultrasonic wave positioning signals and the sound reception basic matrix capable of receiving and 
processing ultrasonic positioning signals; the positioning 
algorithm utilizes internal geometry relations among all basic matrix member signals, does not need the ultrasonic 
signal to reach the 
azimuth of 
array element of the 
matrix array and improves the accuracy of the position solution. The maximum likelihood 
estimation is utilized to perform integral 
processing on the 
signal reaching all the array members after summation in order to obtain a 
global optimal positioning result. Unified resolving is performed on the ultrasonic signals, which is equivalent to improving integration time. As a result, when the 
signal to 
noise ratio of the signals is relatively low, the super-short baseline water sound positioning 
system based on maximum likelihood 
estimation can effectively improves the signal-to-
noise ratio and further guarantee the accuracy of the signals.