600 sea urchins Strongylocentrotus intermedius were randomly chosen from 20 families and the gonad wet weight,gonad index,gonad moisture and fatty acid composition were measured and then analyzed.The results showed that gonad wet weight and gonad index were both significantly different among families(P<0.01),but not between genders,and there was a large gonad yield variance in the measured population; The gonad color of S.intermedius lies between bright yellow and bright orange red,the color was quantified by CIEL^*a^*b^* standard and then ANOVAs were conducted.L^* and a^* components were of no difference among families,but b^* component,ΔE₁ (light yellow) and ΔE₂ (light orangeyellow) were all significantly different among families.The L^*a^*b^* components and the two ΔE_s of the female were superior to male; The family and gender had significant effects on gonad moisture(P<0.01 and P<0.05,respectively); There were relatively high EPA(12.11±2.65)% and AA (10.27±3.40)% contents,but lower DHA(0.49±0.64)% content (with high variation of 130.77%) in the gonad total lipid of S.intermedius.The HUFA was significantly different among families(P<0.01),but there was a significant difference of AA between genders only with the male higher than female.The present study indicated that sex and family selection should be conducted to achieve the goal of the gonad enhancement.