This study was curred out to evaluate the irrigated wheat energy function production and determination of the role of each agricultural input such as water energy in plain Mahiar shahreza region. For this purpose, all inputs used and outputs production, were recored through the collection of field data of 70 randomly selected farmers fields in Mahiar. Then, the equivalent energy of the all inputs and outputs were calculated and the coefficients of Cobb-Douglas and Transcendental equation energy were culculated by regression analysis and the least squares method in the software EViews 5. Energy output can be estimated by inserting the energy inputs in these two equations. Statistical comparisons indicated that the transcendental equation with respect to the energy equation Cobb- Douglas production function with better fit data in energy wheat production. Based on inputs elasticity, the most effective inputs in wheat grain energy were: cultivated area, fertilizer, machinery and consumed water respectively. Water elasticity with -0.05 indicated that water was consumed excessively.