The invention belongs to the technical field of weak-tie call wire power control of large and small power grids, and discloses a method for calculating weak-tie call wire power control strategies of large and small power grids in real time. The method comprises the steps of obtaining call wire power control target information firstly; then enabling an installation and mounting apparatus to monitor and analyze call wire power changing conditions in real time; next, predicting a call wire power changing curve after call wire power abrupt change; then performing prediction and evaluation on a call wire power out-of-limit condition; and finally, calculating the control strategies in real time. By adoption of the method, effective and accurate control of the call wire power in a weak-tie condition of the large and small power grids can be realized, so that the safety and the stability of the large and small power grids in weak-tie operation can be greatly improved, and coordinative development between large power grids and small power grids is promoted.