Abstract: Complex fracture network is easy to form after hydraulic fracturing in coalbed methane reservoir. In order to study the influencing factors of complex fracture conductivity, an improved proppant filling fracture conductivity tester was used to evaluate the effects of proppant particle size, sand concentration, coal elastic modulus, coal powder content and fracturing fluid type on complex fracture conductivity in coalbed methane reservoir. The results show that: under the same sand concentration, the conductivity of E-type fracture is significantly greater than that of T-type fracture and single fracture, that is, the more complex the fracture morphology is, the greater the conductivity is; the conductivity of ceramsite as proppant is significantly greater than that of coated sand and quartz sand; the higher the sand concentration is, the greater the elastic modulus of coal and rock is, the greater the conductivity of fracture is; coal powder and fracturing fluid have great influence on fracture conductivity. The higher the content of coal powder is, the higher the damage rate to fracture conductivity is. Guar gum fracturing fluid has the greatest damage to fracture conductivity, followed by clean fracturing fluid and active hydraulic fracturing fluid. In addition, the more complex the fracture morphology is, the more serious the damage degree of coal powder and fracturing fluid to fracture conductivity is.