Compost leachate is produced from conversion of municipal waste to compost. It containing a significant amounts of organic materials, nutrients, soluble salts and Small amounts of some heavy metals. Adding compost leachate to the soil can pollute it, also improve soil fertility. In this study we Investigated absorption and growth performance of Populus deltoides under irrigation of leachate of Compost Plant of Rasht. At the beginning of the growing season, in mid-March 2013, cuttings were processed from young, 1- year old seedlings of Populus trees at the green house of Populus Research Center of Safrabasteh. Cuttings were planted in pots filled with loamy -sand soil of the vicinity of the area with 40cm depth. Compost leachate was taken from a collection reservoir where leachate from open composting of organic municipal wastes and various gardening and plant wastes had been collected. The leachate was diluted with tap water to avoid direct toxicity due to salinity. Five treatments were applied to plants: (P) pure leachate, (3:1) 3 unit (by volume) of leachate mixed with 1 units of tap water, (1:1), (1:3) and (C) tap water (control). Treatments perform after assurance of seedlings establishment. The growth of the trees was monitored bi-monthly including diameter, height, volume and leaf number measurements. Aboveground (stem, branches and leaves) and root biomass were inventory at the end of growth season. Concentration of elements was determined each three months. Overall, growth parameters in 1:1 and 1:3 treatments were similar together and there are no significant differences between them (p<0.05). Pure treatment had minimum growth, because of high concentration of solvable salts in leachate such as sulfur that causes salinity and high EC in soil. 1:3 treatment exhibited the greatest overall aboveground and root dry mass and it is has significant difference with tap water treatment. There were no significant differences between the rest treatments, therefore leachate didn’t have negative impact. Total aboveground dry mass of leachate treatments and water was 202.25 and 47.58 gr, respectively. Accumulation of elements is more in the plant and soil in high concentrations treatments. N and Ca elements in soil had no significant differ between leachate and water treatments (p<0.05). It means that the elements absorb with plant. P concentration in Pure, 3:1 and 1:1 treatments were more than in other ones with no significant differences (p<0.05). It meant that high Phosphate concentration in leachate. K element show the same result as P.