Four-parameter coalbed methane predicting method and device

The invention discloses a four-parameter coalbed methane predicting method and device and relates to the technical field of coalbed methane exploration and development. The method comprises the following steps that: a Zoeppritz equation set is simplified, so that an elastic modulus approximate expression of the Zoeppritz equation set can be obtained, wherein the elastic modulus approximate formulaof the Zoeppritz equation set is described in the descriptions of the invention, delta k/M in the approximate formula is a volume modulus relative change factor, delta lambda/M in the approximate formula is a lame constant relative change factor, delta mu/M in the approximate formula is a shear modulus relative change factor, and delta rho/rho in the approximate formula is a density relative change factor; under a logging constraint condition, a pre-stack maximum likelihood statistical method is used for carrying out simultaneous inversion on the pre-stack volume modulus relative change factor, the lame constant rela