The invention discloses an on-site capacitance type potential transformer fault detection method, which belongs to the electric power system field and aims to solve the technical problem in the prior art that a capacitance type potential transformer fault cannot be detected conveniently, quickly and instantly. The method of the invention detects through the use of the manner of detecting the voltage of a capacitance unit and an electromagnetic unit, and therefore, capable of rightly determining the unit with capacitance type potential transformer fault from the capacitance unit and an electromagnetic unit. The technical means of the invention are simple, easy to operate, safe and labor-saving. With the method, it is possible to provide onsite testing data for capacitance type potential transformer fault research. Simple and practical in use, the method can complete the capacitance type potential transformer fault detection task quickly, instantly and accurately.