The eunuchs occupied the important position on the tea-Horse trade in the northwest area in the early Ming dynasty. The eunuchs were entrusted with the important tasks. During the Hong Wu Periods in the eighth year ,the First Imperial of Ming sent the official of imperial palace whose name was Zhao Cheng to the Tibet area of northwest to exchange the horse used tea, in the twenty-fifth year, He also sent the master ceremony eunuch whose name was Qing Tong and the imperial kitchen eunuch whose name was Er Nie to the Garrison places of the He Zhou and Bi Li where belonged to Shanxi province to have the horse trading .During the Hong Wu Periods because the strong imperials power and the amplified systems the eunuchs could respect justice and abide by the laws and had the achievements in their official careers ,That situation lasted from the Yong Le periods to the Xuan De periods. After Ying Zong Periods, compared with the smuggling of the Tea-Horse trade and authoritarian politics by the eunuchs, who had play the large role in early Ming dynasty on the Tea-Horse trade. the eunuchs functions should not be underestimated to play the important actions to strengthen the connection of economic and cultural between Ming Dynasty and the northwest Tibetan, and had the effect of maintain the stability of the northwest border area.