This paper constructs a two-country dynamic stochastic general equilibrium model under open economic conditions, to study the impact of small yard high fence policy from US, and empirically analyze the effects of Chinese monetary policy and fiscal policy in response to the policy shocks. It shows that the U.S. implementation of the small yard high fence policy has had a negative impact on the output, the consumption, the price, the net export of China, the value added of export and the position of the global value chain of Chinese high-tech firms. The combination of monetary policy and fiscal policy, by releasing liquidity appropriately and providing targeted fiscal support, can improve the technology and the value added of export of Chinese high-tech firms, leading to high-tech position of global value chains.