The invention discloses a preparation method of a bFGF slow-release gelatin-polyethylene glycol composite gel membrane for myocardial repair. The preparation method comprises the following steps: mixing a gelatin solution and a polyethylene glycol solution, carrying out crosslinking by using a glutaraldehyde solution, conducting washing by using 0.1M glycine and purified water, thus obtaining gelatin-polyethylene glycol composite hydrogel, carrying out freeze drying to obtain a gelatin-polyethylene glycol composite gel membrane, and soaking the gelatin-polyethylene glycol composite gel membrane by using an bFGF solution. After the gelatin-polyethylene glycol composite gel membrane soaked by using the bFGF solution is implanted into the impaired myocardial tissue inside the body, the gelatin-polyethylene glycol composite gel membrane can stably and slowly release bFGF for a long-term, and thus the functional recovery of the myocardial tissue is promoted. The preparation method of the bFGF slow-release gelatin-polyethylene glycol composite gel membrane is easy to operate and low in cost, bFGF can be adsorbed on gelatin molecules through the action of the static electricity, and can be slowly released along with the degradation of the gel membrane, the addition of polyethylene glycol obviously delays the degradation rate of the gel membrane in the body, so that the slow-release time of growth factors is further prolonged, and the release level of the growth factors is stabilized. The bFGF slow-release gelatin-polyethylene glycol composite gel membrane can play an important role in the regenerative medicine field.