The invention discloses a vacuum exhaust system of five-pipeline PECVD (Plasma Enhanced Chemical Vapor Deposition) equipment. The vacuum exhaust system comprises a vacuum pipeline component and an exhaust component, wherein the vacuum pipeline component comprises five vacuum pipelines; one end of each vacuum pipeline is connected with a reaction chamber connection pipeline of a reaction chamber ofthe five-pipeline PECVD equipment; the other ends of the vacuum pipelines are connected with an external vacuum pump; the exhaust component comprises five exhaust pipelines; each exhaust pipeline isconnected with a reaction chamber connection pipeline through a connector; one-way valves and control valves in serial connection are arranged on the exhaust pipelines; the one-way valves are used forintroducing a gas into the exhaust pipelines from the reaction chamber connection pipeline; the control valves are used for controlling on/off of the exhaust pipelines. When too much nitrogen is introduced into the vacuum exhaust system and thus the pressure of the reaction chamber exceeds normal pressure, the nitrogen is output from the exhaust pipeline, is gather with an external exhaust systemand is discharged out; if a pump has faults, gases inside the reaction chamber and the vacuum pipelines can be also discharged out from the exhaust component; and due to adoption of the one-way valves, external air is prevented from flowing into the reaction chamber.