This study relied on laser cladding to prepare a number of Fe-based composite coatings with different WC contents (10-40 wt.%) on the surface of 27SiMn steel. Through an array of research involving the macroscopic/microscopic structure of the WC-Fe interfacial reactive layer, investigation was made into the mechanical properties, the wear behavior of the coatings, as well as the microstructural evolution laws of the WC-Fe reactive layer, and the wear mechanism. Results of microstructural analysis indicate that increasing WC content promotes the formation of a WC-Fe reaction layer by reducing the γ-Fe/WC interfacial energy. In case of a 40% WC content, the maximum thickness reaches 1.3 μm for the WC-Fe interface reaction layer. However, it is prone to incur microcracks at the grain boundaries by the high content and segregation of W element. The findings of the microhardness and fracture toughness imply the best strength–toughness match when the coating WC content is 20% (hardness of 884.7 HV0.2 and fracture toughness of 4.43 MPa m1/2). Naturally, it reveals the best surface flatness in the wear test owing to the solid solution of the W element and the diffuse distribution of carbide particles. On the contrary, the coating with 40% WC content underscores the worst hardness and toughness (hardness of 554.6 HV0.2, fracture toughness of 2.98 MPa m1/2). It also accidentally demonstrates commendable wear resistance. This may pertain to a unique self-lubricating layer and the microcracked stress buffering network structure on the coating surface, which further ascertains a new wear resistance mechanism of the microcracked network.