Objectives The effects of different levels of nutrition in feed on the performance of fattening and economic benefits of hybrid beef cattle were studied to optimize the nutrition formula and fattening plan for hybrid beef cattle. Methods 90 Simmental crossbred bulls with similar body weight, physical condition, and health were randomly divided into the experimental group Ⅰfed with high level of protein in diet, the group Ⅱ fed with medium level of protein in diet and the group Ⅲ fed with low high level of protein in diet. The feeding experiment lasted 300 days. The body weight, the cost of feed, and the economic benefits of beef cattle were measured and analyzed. Results The total weight gain in the group I, group Ⅱ and group Ⅲ reached 277.7-337.1 kg, with an average daily gain of 925.7-1 123.6 g. The difference in total weight gain and average daily weight gain during the period of fattening between the experimental group I and the experimental group Ⅱ was not significant (P>0.05), but both were significantly higher than that in the experimental group Ⅲ (P<0.05). The cost of feed in the experimental group Ⅲ during the period of fattening was the highest, reaching 6 558 yuan/head, followed by that in the experimental group Ⅱ and the experimental group I, at 5 796 yuan/head and 5 298 yuan/head, respectively. The net profit in the experimental group Ⅱ was 1 242 yuan/head, which was the highest among the three experimental groups, higher than that in the experimental group I and the experimental group Ⅲ at 543 yuan/head and 519 yuan/head, respectively. Conclusions It can be determined that the level of nutrition in the experimental group Ⅱ is most suitable for fattening hybrid beef cattle based on comprehensively analyzing the weight gain and economic benefits in each experimental group during the period of fattening.