A multi-outdoor unit parallel type non-reversing defrosting system, comprising an indoor heat exchanger and three or more outdoor units arranged in parallel, wherein the outdoor units each comprise a compressor , a four-way valve , an outdoor heat exchanger , and a first solenoid valve ,; four interfaces of the four-way valve are connected to a discharge end of the compressor , an air return end of the compressor , the first solenoid valve , and the outdoor heat exchanger , respectively; the first solenoid valves of the outdoor units are converged and connected to one end of the indoor heat exchanger , and the outdoor heat exchangers of the outdoor units are converged and connected to the other end of the indoor heat exchanger ; characterized in that the multi-outdoor unit parallel type non-reversing defrosting system further comprises a bypass branch; both ends of the bypass branch are respectively in bypass connection to a pipeline between the four-way valve and the outdoor heat exchanger and a pipeline between the first solenoid valve and the indoor heat exchanger ; the bypass branch is provided with a second solenoid valve configured to control connection and disconnection of the bypass branch; and wherein the multi-outdoor unit parallel type non-reversing defrosting system is configured so that when it is monitored that any outdoor unit is abnormal in frosting, the outdoor units which are not frosted are correspondingly distributed and started as required on the basis of a current heating energy requirement A of the indoor heat exchanger , and after the started outdoor units run to a target frequency, the outdoor units are correspondingly distributed and started as required on the basis of the heating energy requirement A and a defrosting energy requirement B of the frosted outdoor unit , and meanwhile, the bypass branch of the frosted outdoor unit is controlled to be connected till it is monitored that defrosting is completed. characterized in that the multi-outdoor unit parallel type non-reversing defrosting system further comprises a bypass branch; both ends of the bypass branch are respectively in bypass connection to a pipeline between the four-way valve and the outdoor heat exchanger and a pipeline between the first solenoid valve and the indoor heat exchanger ; the bypass branch is provided with a second solenoid valve configured to control connection and disconnection of the bypass branch; and wherein the multi-outdoor unit parallel type non-reversing defrosting system is configured so that when it is monitored that any outdoor unit is abnormal in frosting, the outdoor units which are not frosted are correspondingly distributed and started as required on the basis of a current heating energy requirement A of the indoor heat exchanger , and after the started outdoor units run to a target frequency, the outdoor units are correspondingly distributed and started as required on the basis of the heating energy requirement A and a defrosting energy requirement B of the frosted outdoor unit , and meanwhile, the bypass branch of the frosted outdoor unit is controlled to be connected till it is monitored that defrosting is completed. <EOS>