Abstract: Phenotypic traits are the core selection standards in breeding of new varieties.We chose 73 wild Pyropia haitanensis strains as experimental material which collected from Fujian coast.We analyzed the genetic diversity of P.haitanensis through phenotype data including 5 basic morphological characteristics and 14 quantitative traits.The results indicated that 4 morphological characteristics including leaf type, color, sawtooth and distortion degree had extremeby significant (P<0.01) relationships with 4 quantitative traits including the length, width, fresh weight and thickness.In addition, the base shape of thallus significantly(P<0.05) correlated with the length, width, fresh weight and thickness.By comparing the average values of different traits, we found that linear thallus showed the highest length growth rate, the thallus with heart shape base exhibited the highest weight growth rate, thallus without sawtooth was the thinnest strain.According to the results of nested analysis on variance among strains, the mean variance components was 72.79% among strains which far larger than mean variance components of 21.46% within strains, which explained the main source of P.haitanensis phenotypic variation originate between strains.We also found that coefficient of phenotypic variation of P.haitanensis thallus was ranged from 7.14% to 35.45%, and the variation coefficient of thickness was the lowest, while the mean weight per thallus was the highest.These indicated that thickness only had little potential to improve, but weight was worth to be the target trait.Present study could offer some basic information for future P.haitanensis breeding.