This study was performed to establish in vitro gametophytes production system of Cratoneuron decipiens mosses by several chemical and physical environmental factors affecting micropropagation. In vitro cultures were initiated from apical shoot, leaves of gametophytes with respective concentration of commercial bleach, and time combinations. High percentages of survivability were found with 1% NaOCl for 2 min sterilization on culture derived from both the gametophytes tips and leaves. Gametophytes were successfully produced by subculture of apical shoots, basal shoots, and chopped gametophytes. The numbers of gametophytes per culture flax were greatest in chopped gametophytes culture among all the culture types. Seven types of culture media and four types of total nitrogen and sucrose concentrations were tested for gametophytes production. Knop macro salts and Nitsch and Nitsch trace elements were most convenient among types of media. Respective light and temperature factors were also evaluated for micropropagation of this moss. Higher sucrose concentrations tended to have a negative effect on elongation and numbers of gametophytes. Nitrogen deficiency and excessiveness both inhibited growth of gametophytes. Temperature variation caused highly significant changes in number, length and fresh weight gametophytes. A common optimum seems to be around 2000 - 3000 lux for proper growth of gametophytes. All developmental aspects of the moss species studied were governed by the external environments.