Regular observation of near surface air temperature in Tianjin began in October 1890. There is a temperature series over 110 years and the continuity of the temperature observations has been well conserved. However, there seems to be considerable inhomogeneity in the series before 1951 with less metadata can be collected. Unfortunately as well, there is no available reference series can be used to detect the possible inhomogeneity. In this paper, the inhomogeneity in daily minimum and maximum temperature observations in Tianjin from 1891 to 1950 was examined and adjusted using the RHtestV3 software package, without reliable reference series available. To verify the rationality of the adjustment, multiple temperature series from areas around Tianjin were collected from different sources and employed as consistency references. The examination indicated 6 breakpoints in the minimum temperature series mainly during 1897-1927 and 2 breakpoints in the maximum temperature series in February 1919 and January 1932. Annual mean temperatures are calculated as the mean of the adjusted minimum and maximum temperatures and the series is much better related with the consistency references and resulted in a trend of climate warming close to the average trend of North China, which verified the homogenization in the adjusted Tianjin temperature series.