This research aimed to study privatization effect on enhancing development of stock market. Privatization is a financial and juridical process which governments use in order to reform economy and administerial system in country. According to privatization literary, meaning the purposes of privatization is to enhance guild effectiveness, proper distribution of earning, government miniaturization, empower the private branch, enhance stock market, increase competition and provide consumers revenue by entrusting the ownership and generalship of governmental political guilds to non-government branches in financial, economical and social-political ambits. The population of this research consists of all companies listed in Tehran’s stock market during the period of 1379 to 1387. Since this paper aims to study general state of stock market there is no need to select a sample. In order to evaluate effect of privatization on stock market development, according to spotted index, by using Perron test, proceed with probable structural break points in 9 dates, according to trend of privatization. Result of the research showed that privatization does not affect on stock market development. A reason of this finding could be Iran’s incorrect process of privatization.