The invention discloses a chromatographic test device capable of prolonging the lifespan of a chromatographic column and a detection method thereof, and solves the technical problem that the existing power insulating oil chromatographic test is high in cost. By a mode of once sample injection and twice flow division, the content measurement can be carried out by effectively using the samples separated by the chromatographic column, and after flowing out of a front chromatographic column 4, gas such as CO2, C2H4 and C2H2 directly passes through a rear chromatographic column 15, so that the content of relevant components is lost or the relevant components are adsorbed by a molecular sieve, and a result cannot be detected or is affected; meanwhile, according to the method, the sample injection amount of the chromatographic columns can be effectively controlled or reduced within reasonable detection range, so that the service life of the chromatographic column can be prolonged, and the column separation efficiency of the chromatographic column is improved; the front chromatographic column 4 and the rear chromatographic column 15 are different in the aspect of separated chromatographic components. The service life of the chromatographic column can be efficiently prolonged, the chromatographic column separation degree is increased, and the stability and the accuracy of test data are guaranteed.