The invention discloses a transmitting power allocation method of a wireless communication sub-channel, comprising the following steps of: (1) calculating Pn according to a formula, wherein n may be 1, 2, ..., N; (2) counting the number X of Pns less than zero and a total value of the Pns, and setting values of the Pns less than zero to be zero; (3) downwards translating Pns greater than zero; and (4) judging whether all the translated Pns are not less than zero or not, returning to the step (2) if not all the translated Pns are not less than zero, and finishing the algorithm if all the translated Pns are not less than zero. By using the transmitting power allocation method of the wireless communication sub-channel provided by the invention, the searching of a Lagrange constant is avoided to obtain an optimal power allocation scheme in an over-zero regulation way by utilizing the translation characteristics of the conventional water-filling algorithm, so the complexity of the algorithm is reduced, the requirements of real-time power allocation and power regulation are met, the operation time of the algorithm is shortened, simultaneously energy consumption for the running of the algorithm is reduced and importance to a mobile communication terminal with dependence on a battery for power supply is ensured. The transmitting power allocation method of the wireless communication sub-channel of the invention is faster and simpler than the water-filling algorithm which uses binary search Lagrange content.