The invention relates to a content determination method for coleus forskohlii capsules. The method adopts high performance liquid chromatography, and includes the steps of: 1. weighing an isoforskolin reference substance, adding methanol to prepare a solution with a content of 0.1-0.3mg / ml; 2. taking coleus forskohlii capsules, pouring out the contents, mixing the contents evenly, taking 1 part of the mixture, adding 30-100 parts of ethanol, conducting ultrasonic treatment (or backflow, soxhlet extraction), performing filtration, taking subsequent filtrate, carrying out evaporation to dryness, or not using the aforementioned extraction method, adding 2-4 parts of silica gel and 5-7 parts of ethanol, blending the substances evenly, carrying out evaporation to dryness, grinding the substances evenly, then transferring the substances to a silica gel column, employing 120-180 parts of a petroleum ether-ethyl acetate mixed solution in a volume ratio of 3:1 to perform elution, collecting the eluent, transferring the eluent to a silica gel column containing 3-8 parts of 2-4% AgNO3, discarding the effluent, using a mixed solution of petroleum ether and ethyl acetate in a volume ratio of 2:1 to perform elution, discarding the eluent, then using 90-180 parts of a mixed solution of petroleum ether and ethyl acetate in a volume ratio of 3:1 to perform elution, collecting the eluent, conducting evaporation to dryness, performing dissolution with methanol, and transferring the product into a 2-5 times measuring flask, adding methanol to scale, and performing filtration; and 3. sucking 5-20microl of the reference substance solution and the test solution respectively, injecting the solutions into a liquid chromatograph to obtain a chromatogram, and calculating the content of the effective component isoforskolin in the test solution according to the chromatogram.