A method of spatial reuse with opportunistic transmit power control (TPC) and clear channel assessment (CCA) is proposed. In the opportunistic TPC and CCA, a spatial reuse station (SR-STA) gains enough knowledge in certain situation for more aggressive spatial reuse such that its transmit power may be adjusted to meet the spatial reuse conditions based on the received OBSS PPDU and the corresponding spatial reuse parameter (SRP). Both Type 1 SRP and Type 2 SRP are defined. In one example, the Type 1 or Type 2 SRP is a 5-bit parameter carried in the HE-SIG-A field of the OBSS PPDU, which can be a trigger frame, a response frame, a request-to-send (RTS)/clear-to-send (CTS) frame, and a data frame.