A low-viscosity and solvent-free polyurethane adhesive was prepared with mix of polyester and polyether polyols, and IPDI as main raw material. The influences of polyester to polyether ratio on reaction time, viscosity, and water resistance as well as adhesive strength were studied. The influences of catalysts' addition on over-all properties of the adhesive were discussed. The results showed that polyurethane adhesives compounded by mixing of polyester and polyether polyols has low viscosity and is easy to smear; OH mole ratio must be well controlled, and the best ratio is 0.3/0.7; addition of catalysts raises the curing speed and reduces the peel strength, which means catalysts is not in favor of the comprehensive performance of adhesives. Thus, the circumstances should be taken into consideration when adding catalysts.