How to design mutual inductor in proteus for wireless charging?
You'll have to build the model yourself, according to the circuit below.

The Primary Inductance can be simply the inductance of your primary coil on its own. So either model it, calculate it from the dimensions and number of turns, or simply wind the thing and measure it.

The Leakage Inductance is measured the same way, i.e. by measuring the primary inductance again, but with the secondary coil in its proper place with its output short circuited. Modelling it or calculating it is likely to be hit or miss, and its actual value will be critically dependent on the relative positions of the two coils, so most easily determined by actual measurement.

The transformer is an "ideal transformer" whose turns ratio is the same as your two coils.







simulate this circuit &ndash; Schematic created using CircuitLab

An accurate model would also include both winding resistances and capacitances, but this should serve as a starting point.