A method for optimally determining sensor positions for an acoustic pyrometry, capable of obtaining a minimum number of sensors satisfying a given error limit and determining positions of the obtained number of sensors for error minimization, in which a predetermined number of sensors are arbitrarily arranged on sides of a rectangular sectional area to be measured and a transfer matrix is calculated with respect to positions of all the sensors, with effective independence values obtained for respective paths of each of the sensors by performing singular value decomposition with respect to the calculated transfer matrix and a total effective independence value of each of the sensors is obtained by summing up the effective independence values obtained for the respective paths, followed by having a smallest one of the obtained total effective independence valves removed from among the sensors and the above steps are repeated until the number of the remaining sensors becomes equal to a target valve.