The main problem of 500kV short-circuit current overweight has become one of the most prominent issues of Guangdong power grid in recent years. The existing operation measures can reduce excessive short-circuit current to safe levels temporarily, but the short circuit current level of the whole power grid is still high, with sacrificing the part safety and reliability of the system. In the long run, limiting short-circuit current through the back-to-back HVDC asynchronous interconnection is a feasible solution. Guangdong 500kV power grid in 2018 as the research object, the model of back-to-back HVDC asynchronous interconnection is established. And with the simulation of the short circuit current limiting effect and the system reliability, compared with traditional operation measures, we can obtain that back-to-back HVDC asynchronous interconnection has better short circuit current limiting effect and higher safety and reliability. The effectiveness and superiority of the scheme in short-circuit current limiting is verified.