This paper expounded the application of "collateral-qi moving rapid" in the treatment of pyretic arthralgia from the concept of "collateral-qi moving rapid" , the etiology and pathogenesis of pyretic arthralgia, the relationship between pyretic arthralgia and "collateral-qi moving rapid" , as well as the application of "collateral-qi moving rapid" in the treatment of pyretic arthralgia. One proven case was presented.