The invention discloses a polyurethane composite material and a forming method of a dumbbell piece. The polyurethane composite material comprise two components including a prepolymer component and a polyol component, wherein the prepolymer component is a prepolymer which has an NCO content of 10-20% and is obtained by reacting mixed isocyanate with propylene oxide polyether polyol having a functionality of 2 or 3, the mixed isocyanate is selected from two mixtures consisting of polymeric MDI and one of MDI or MD150, and the weight of the polymeric MDI is 10-90% of the total amount of the mixedisocyanate; the polyol component is a component obtained by mixing propylene oxide polyether polyol with a functionality of 3 with a curing agent and a catalyst, and dehydrating the mixture until thewater content is less than 0.05%; the mixed curing agent is a mixture of an amine curing agent with the functionality of 2 and an alcohol amine curing agent with the functionality of 3, and the alcohol amine curing agent with the functionality of 3 accounts for 5%-10% of the total amount of the mixed curing agent. The prepolymer component and the polyol component are mixed according to the mass ratio of 100: (90-200), the material temperature is 30-40 DEG C, the mold temperature is 60-70 DEG C, the mixture is poured into a mold with a dumbbell piece metal core, and demolding is carried out 10-15 minutes later to obtain the product.