The invention discloses a method for detectingprotein interaction by co-immunoprecipitation on the basis of two-color fluorescent tag proteins GFP and mCherry. The method comprises steps as follows: target genes are constructed to N ends of expression vectors respectively, agrobacteria are transformed after plasmid is extracted, agrobacterium infection liquid co-injection model plant is prepared,a co-injection tobacco leaf protein is extracted, target proteins with GFP tags are enriched with GFP-Trap A beads, meanwhile, other target proteins with mCherry tagsare immunized, and finally, expression and interaction conditions of the target proteins before immunization and after immunization are detected by the GFP and mCherry tag antibodies respectively. According to the method, while real-time fluorescent visual monitoring for expression and co-localization of the target proteins in living cells is realized,the protein interaction can be directly and effectively verified through the co-immunoprecipitationby selecting the stage of the highest expression quantity in real time, the success rate of protein interaction verification is greatly increased, and time and economic cost is substantially reduced.