This search was conducted during 2014-2015 growing season in Agricultural research station in Al Kraeim belonging to Al Salameah district in Hamah Provence in order to study the effect of plant density on; First, the phenological stages of lentil plant calculated in day unit. Second, the seed productivity in a lentil plant calculated in g/plant, and then seed production in Hectares (Kg/ha-1).Lastly, percentage of seed protein content in seeds. In this study, three plant densities were used (200, 250, 300 seeds/m2, and was designed using Randomized Sectors in three replicates for each density. Results showed that; 1) The low density plants (200 seeds/m2) was significantly better than other densities (250 and 300 seeds/m2) in: Reaching 50% seed germination (19.4, 20.5 and 22.5 day continually) and in flowering stage (111.36, 113.6 and 114.7 day continually) and in maturation/Ripening stage (134.4, 136.6 and 137.7 day continually). Seed production per plant (1.553g/plant) in comparison by seed production of other densities (1.487 and1.376 g/plant). Percentage of seed protein (26.8%) in comparison by seed protein of other densities (26.3 and 26.19 %). 2) The higher densities (300 seeds/m2) was better in seed production in aria unit (1791.3 Kg/ha-1) in comparison by production of other densities (1492.7 and 1194.2 Kg/ ha-1).