The embodiments of the invention relate to the technical field of plasma chemistry vapor deposition, in particular to chemical vapor deposition equipment and a constant pressure raw material protection device thereof. The constant pressure raw material protection device includes an air source, a first control valve, a first pressure regulating valve, a buffering tank, a second pressure regulatingvalve, a monomer tank assembly, a second control valve, and a vacuum pump device which are in communication in sequence through a pipeline, wherein the first control valve and the second valve both have communication states and disconnection states, when the first control valve is located in the disconnection state, and the second control valve is located in the communication state, the air sourceis disconnected from the buffering tank and the monomer tank assembly, the vacuum pumping device is in communication with the buffering tank and the monomer tank assembly, and the pipeline is vacuumized through the vacuum pumping device to isolate the air source from air. The constant pressure raw material protection device has the characteristics that the air can be isolated, air source pressureis stable, the pipeline is cleaned quickly, and control is easy.