Abstract: In order to provide theoretical basis for the manual control regulation of intercropping system that existed allelochemicals, pot experiment was carried out to research the effect of eugenol on crop growth rate and grain yield of wheat faba/bean intercropping system at water application of 75%, 60% and 45% field capacity. The results showed that eugenol could inhibite the crop growth rate (CGR)of fava bean in the seedling-beginning flower and pod setting-mature period of faba bean, except sole faba bean with 75% water supply level and the intercropped faba bean with 60% water supply level, increased water supply can alleviate the inhitory action of eugenol on the sole faba bean, but the inhitory action of eugenol on the intercropped fava bean exacerbate, intercropping planting pattern can alleviate the inhitory action; eugenol could inhibite the wheat CGR after seedling period, increasing water supply can not alleviate the inhitory action of eugenol, intercropping planting pattern can alleviate the inhitory action of eugenol on the wheat CGR at the stage of flowering to maturity. Compared to weighted average sole grain yield, intercropped grain yield was increased by 24.92%~52.74% under the same water supply. Other treatments showed that allelopathy has inhibitory effect on the grain yield of two crops except 45%water supply level. Intercropping planting pattern can alleviate the allelopathy of eugeno on the wheat, fava bean grain yield