The paper focuses on some of the biological characteristics of golden grey mullet, Liza aurata in Iranian waters of the Caspian Sea. Samples of commercial catch of mullet obtained by means of beach seine fishing cooperatives along the Iranian coasts of Caspian Sea (2007-2008) as monthly interval. Samples subjected to biometric measurement to specify their biological characteristics. The male/female ratio in the present study was 1:1.22 which deviated significantly from 1:1common sex ratio (X2=7.7, Sig, level=0.006). During this study, the peak of the spawning time for golden grey mullet occurred in October in waters off- Guilan shore whereas it occurred in November off Mazandaran and Golestan provinces. The highest Gonado-Somatic Index (GSI) was found to occur during late September and October which declined to its lowest level in November and December and remained relatively stable during January to April. Therefore spawning of L.aurata started earlier in Guilan and ended later in Golestan Province.The average absolute fecundity of the golden grey mullet was 700881 429987 ( SD) eggs with a range of 200112 and 2282862 eggs. The length of female at 50% sexual maturity of golden grey mullet was estimated 28.4 cm.