Abstract: The two solar calendars inherited by the ancient people of Yi are all objectively based on the solar tropical year. One of them is to divide a year into ten months with 36 days in each month, as the Ten-Month Calendar. The other is to divide a year into 18 months with 20 days per month, as Eighteen-Month Calendar. In ancient times they were also referenced as 20 Throttle Calendar or 30 Throttle Calendar (12 days in each solar term). Mr. Liu, Han-Yao frequently pointed out that these are two different calendars and were created by the ancient Yi people. In this paper it is described that these three conclusions have no foundation and are the subjective assumption. The Ten-Month Calendar and the Eighteen-Month Calendar are linked with each other, but their forms are different. The Eighteen-Month Calendar was not created by the Yi people, but only inherited. The difference is that the Ten-Month Calendar gives the Yin and Yang and the five elements etc. more philosophical meaning.