It is of great practical significance to study the robustness of networked CPS(cyber physical systems) under cascading failure. A two-tier asymmetric dependency network model was constructed for CPS with one-way dependency and a cascading failure model for asymmetric dependency network which combines the dependency failure with the overload failure was designed. A more practical asymmetric attack method was proposed, and a node capacity allocation method under resource constraints was given. Simulation experiments were carried out on asymmetric dependent networks consisting of scale-free subnets. It is found that the network robustness is positively correlated with the sub-network average, degree exponent, node capacity, etc.; assortative dependency networks and networks with node capacity allocation by degree are more robust; asymmetric dependent networks are vulnerable to attention attacks; when attacking dependent subnets with equal strength, the network is more vulnerable. The constructed model and the law of experimental discovery have certain reference value for studying network robustness and optimizing network design.