Abstract: In order to improve the utilization rate of fertilizer and protect agricultural ecological environment, the field test was used to study the influence of poly amino acid synergist on vegetable growth and yield. The results showed that compared with the traditional fertilization, the treatments of poly amino acid synergist increased the eggplant plant height, leaf width and yield by 5.6% ~ 11.1%, 7.1% ~ 14.3% and 3.1% ~ 11.8% respectively; and increased the cabbage plant height, leaf width and yield by 6.2% ~ 13.4%, 9.1% ~ 12.7% and 2.5% ~ 5.8% respectively. The results also showed that when vegetable growth period was in two months, the treatment of compound fertilizer + urea + 2 ‰ poly amino acid synergist obtained higher yield; When vegetable growth period was more than two months, the treatments of compound fertilizer + urea + 2 ‰ (3 ‰ or 4 ‰) poly amino acid synergist + 7 ‰ NAM inhibitor were recommend in practice. Poly amino acid synergistic agent is a kind of polymer, with the functions of conserving soil water, combining and activating soil nutrient. At the same time, with the biodegradable property, under the action of soil enzymes, it can be completely degraded into free amino acids, and absorbed and utilized by crops, without any residual and secondary pollution. Therefore, the poly amino acid synergist is a kind of environment friendly fertilizer synergist, and should be appropriately promoted in the agricultural production.