Abstract: Red algae is one of the dominant algal species in the eastern Pacific Ocean, get its biomass information can help to know the significant role of phytoplankton in marine chemical circulation and the process of energy exchange. The diagnostic pigments contained in red algae are the key to accurately obtain biomass information, so it is of great scientific value to carry out inversion research on the diagnostic pigments of red algae. Based on the data of six eastern Pacific Ocean cruises, this paper constructed inversion models for the diagnostic pigments of red algae by using the “co-variation effect” between three diagnostic pigments of red algae (chlorophyll c1+c2, chlorophyll c3 and 19’-hexanoyloxyfucoxanthin) and the total chlorophyll a. The model validation results show that the R² is between 0.68 and 0.88 (p<0.001), the mean absolute percentage error ranges from 39% to 46%, and the median error is less than 30%. The results show that the concentrations of diagnostic pigment in the eastern Pacific Ocean are high in the coastal area and low in the ocean, which have obvious seasonal variation characteristics. The diagnostic pigment of red algae inversion models constructed in this paper can provide data bases and method supports for characterizing the distribution of red algae community and monitoring algal bloom disasters.