To investigate the performance of maize - mung bean intercropping using different seeding ratios (1:1 , 1:2 and 2:1) in the west of Iraq; a field experiment was conducted in spring and autumn seasons of 2013 using complete blocks design(RCBD) with three replicates, the equivalent and competition indicators were estimated. The result showed the following: the yield of total dry matter and grain yield of maize as individual were superior in comparison with intercropping with mung bean. The intercropping of maize and mung bean recorded a higher than 1 of land equivalent ratio (LER), seeding ratio 1:1 gave the higher (LER) of grain yield in the spring reached 1.10, while seeding rate 2:1 gave the higher (LER) of dry matter in the autumn (LER 1.08). Maize showed greater ability of Aggressively (A) in intercropping with mung bean compared with mung bean, where showed the positive values while the mung bean recorded negative values of (A) at the all seeding ratios, maiz gave the higher values of (A) reached 0.21 of dry matter at seeding ratio 1:1 in the spring season and 0.22 at 2:1 in the autumn. Maize also showed the most aggressivity of grain yield where gave 0.28 at seeding ratio 1:1 in the spring and 0.36 at seeding ratio of 1:2 in the autumn. It can be concluded that the relation between maize and mung bean is a competitive more than symbiosis under current experiment conditions.