Two method was used to analysis the trend of meteorological diffusivity for fine particulate in Tianjin since 2000. One is simulating PM_2.5 mass concentration by WRF/chem in Tianjin from 2000 to 2015 with same high precision emission. The other is analyzing a fine particulate meteorological diffusion index constructing from NCEP data and ground observation. There is an obviously periodic fluctuation of meteorological diffusivity for fine particulate from 2000 to 2015. There are two peak of low meteorology diffusivity. The first one is from 2003 to 2004 and another is from 2013 to 2015. There are 11 years interval between the two peaks. The inter annual variability for meteorological diffusivity of fine particulate has a averaged 4.1% value and max 9%value. The inter annual variability must be considered for atmospheric pollution control and evaluation. The good meteorological diffusivity for fine particulate is from 2008 to 2010. After that, the meteorological diffusivity get worse year by year and reach peak value from 2013 to 2015 which causing the frequently haze and heavy pollution weather. Comparing with 2013, the observed PM_2.5 mass concentration decreased 29% on 2015 with same meteorological diffusivity. It implies that the atmospheric pollution control method worked effectively. comprehensive meteorological diffusion function, described the change tendency of the 21st century polluted meteorological conditions. The result showed:The polluted meteorological conditions Showed the cycle fluctuation form 2000 to 2015, the first peak of adverse weather conditions was 2003~2004, the second peak of adverse weather conditions was 2013~2015, the apart of two peaks was 11 years. Inter annual fluctuation of The polluted meteorological conditions (mainly for PM_2.5) was about 4.1%, the maximum was about 9%, The goal and effect of atmospheric pollution control was set, meteorological cycle fluctuations must be considered. Polluted meteorological conditions was conducive to atmospheric pollutants diffusion from 2008 to 2010, then turn worse year by year, which led to haze and heavy pollution weather frequent form 2013~2015. Compared to 2013, Tianjin pollution meteorological was not turned for the better on 2015, but PM_2.5 dropped 29%. Atmospheric pollution control was effective on Tianjin.