Random Amplified Polymorphic DNA (RAPD) technique and morphological characters analysis were used to investigate the growth and variation of four consecutively selected lines (black, white, red, yellow shell colors) of Pinctada martensii, with the aim of providing theoretical basis for further selection.The results showed that in four F3 generation of selective lines of P.martensii shell color purification rates were 95.83% for black, 88.33% for white, 100% for red and 95.0% for yellow shell color respectively.the growth rate of selected lines of the four shell colors were greater than that of the unselected population, there also existed significant difference between the selective lines in terms of growth rate.The polymorphic loci percentages (P) in four lines were 82.51%, 81.93%, 75.30% and 77.03%, respectively.Nei's gene diversity (H) was 0.233 6, 0.213 4, 0.196 5 and 0.201 9, respectively, and Shannon information indexes (Hi) were 0.351 6, 0.323 0, 0.279 9, 0.305 9, respectively.The genetic differentiation (G_st) between four lines were from 0.214 3 to 0.318 6.The mean genetic distances (D_xy) were 0.113 5 between black and white, 0.130 3 between white and yellow, 0.134 9 between black and yellow, 0.154 6 between white and red, 0.158 4 between red and yellow, 0.196 8 between black and red, respectively.Cluster analysis showed that the genetic relationships from near to far between four shell color lines were black, white, yellow and red.There existed higher genetic diversity in each selected line.Higher genetic differentiations were present between selected lines.Resultsof the study can provide theoretical support for the directed selection of four shell color lines of P.martensii.