The invention provides a multi-parallel type traveling wave thermo-acoustic engine system. The system comprises a plurality of thermo-acoustic engine units (14) which are connected in series end to end through resonant tubes (12) to form a loop. Each thermo-acoustic engine unit (14) comprises a main room-temperature heat exchanger (1), multiple grades of parallel structures and an auxiliary room-temperature heat exchanger (11), wherein the main room-temperature heat exchanger (1), the multiple grades of parallel structures and the auxiliary room-temperature heat exchanger (11) communicate in sequence. Each grade of parallel structure comprises a regenerator, a heat end heat exchanger and a heat buffer pipe, wherein the regenerator, the heat end heat exchanger and the heat buffer pipe are sequentially connected. The working temperatures of the heat end heat exchangers in the multiple stages of parallel structures are gradually decreased in the same direction to form cascade working temperatures, and thus gradient utilization of a variable-temperature heat source is achieved. According to the system, gradient utilization of the variable-temperature heat source is achieved in each thermo-acoustic engine unit through the parallel structures, and the system is compact in structure and high in energy utilization efficiency; and meanwhile, application occasions with different power requirements can be met through the multi-parallel structures of the multiple units.