The study was carried out at the College of Agriculture University of Anbar during the spring season of 2018, the study conducted by using water for irrigation with different electrical conductivity (1.1, 3.00, 5.00, and 7.00 Decimeters M-1) which marked as W1, W2, W3, and W4. This study has included three experiments. The field experiment used water for irrigation with different electrical conductivity (1.1, 3.00, 5.00, and 7.00 Decimeters M-1) and three levels of humic acids were used: (0, 20 and 40 kg.H-1) H0, H1 and H2. Also, there are three levels of mono superphosphate fertilizer were used: P0, P1, and P2 (0, 100, and 150 kg. E-1). to estimate of heterosis on some growth properties of onion yield. The results showed decrease for plant's height when the salinity of irrigation water increased. while the leaf’s area, and the stem diameter increased by decreasing salinity at the level 7 decimeters M-1, the leaf's area, and the stem diameter increased increasing by adding humic acid levels and phosphate fertilizer levels. The results showed decrease in the total yield, by increase in the salinity of irrigation water from 1.1 to 7 decimeters M-1, while the total yield was increased by adding humic acid and phosphate fertilizer levels.