Disclosed is an adaptive downlink packet transmission method for a multicarrier Code Division Multiple Access (MC-CDMA) system. The method can allocate radio resources efficiently according to the variations of channel conditions for each user terminal, allocate transmission power appropriately according to the interference from the same cell, and minimize interference to adjacent cells. The adaptive downlink packet transmission method includes the steps of: a) estimating a signal-to-interference-and-noise ratio (SINR) in a user terminal after channel equalization and despreading by measuring a downlink pilot channel; b) measuring an average interference factor and an average noise power; and c) allocating radio resources adaptively in the central station by determining transmission slots in a transmission frame, the number of spreading codes to be used in each transmission slot, symbol energy for each spreading code, and a transmission method, until transmission slots and packets to be allocated are not available.