This paper describes a calculation method of large-signal characteristics of multi-stage power amplifier modules using source-pull and load-pull data. An output power, a power-added efficiency, and a phase deviation of multi-stage power amplifier modules are calculated based on the source-pull and load-pull data, which are comprised of input and output reflection coefficients, an input power, an output power, a phase deviation and a drain voltage and current, taking into account the source and load impedance of each stage FET. Applying this method to a 900 MHz two-stage Si-MOSFET power amplifier module, the calculated and measured results are in good agreement.