Protein-protein interaction (PPI) serves as a fundamental regulatory mechanism that mediates diverse biological processes to govern cellular activities. The identification of protein-protein interactions is a pivotal technique for accurately analyzing protein function and systematically elucidating its regulatory mechanisms. Immunoprecipitation-mass spectrometry (IP-MS) represents a commonly employed approach for identifying protein-protein interactions in cells. Mass spectrometry enables the verification of both known protein interactions and the discovery of unknown proteins interacting with target proteins, providing not only information on the presence of proteins in samples but also facilitating comparative analysis of their relative abundance across different samples. In this chapter, we present a method for immunoprecipitating protein complexes from total plant protein extracts, followed by mass spectrometry (IP-MS), to identify the interaction between proteins in strawberry fruit.