Climate comfortable period (CCP) is a temporal index evaluating the climate comfortableness or human thermal comfortableness. It is of significance to architectural design, public health and tourism development etc. Most of studies on CCP generally take month-scale as the time granularity, which is too long to precisely chart the intra- or inter- regional differences, especially under global climate change. This article chooses day-scale as the time granularity of CCP, which is more precise than month-scale. Based on the daily meteorological data from 775 basic weather stations in the mainland of China from 1961 to 2010, which is provided by China Meteorological Science Data Sharing Service Network, this paper makes use of Temperature Humidity Index (THI) and Wind Effect Index (WEI), and modifies them to fit the actual situation of China in order to assess the climate comfortableness in the mainland of China since the 1960s. This study indicates the average annual and seasonal CCP and its spatial patterns in the mainland of China, and summarizes the evolving characteristics of CCP over the past 50 years. These results can provide some scientific understandings for human settlements environmental constructions, and also be helpful to improve local or regional resilience responding to global climate change.