Abstract: Using radiosonde data and planar fitting, large-scale heat and moisture budgets over part of the Yangtze River through May 1 to July 31 in 1983 are evaluated, emphasizing comparisons of apparent heat source and sink both before and after the Meiyu. It is found as follows:1)The heat source for Meiyu formed with condensation by precipitation. It was usually at 700-400 hPa, sometimes up to 400-300 hPa. So was the heat sink. The Meiyu was characterized by continuous rain with weak convection.The atmosphere in the area was similar to that in the tropics. Q₁ and Q₂ were mostly contributed by the vertical advection terms. The horizontal advection terms dominated in the upper level while the local change terms remained a minor role.2)Despite its stable and continuous feature, the 1983 Meiyu had marked diumal variation in rainfall. Generally, there is mainly cooling in the morning and heating in the afternoon, or concentrated heating（implying precipitation） shifted from middle and lower levels in the morning to upper levels in the afternoon.3) Both evaporation and upward transfer of sensible heating were important factors in heat and moisture budget during dry spells;4) A comparison between 1979 and 1984 work showed that the Meiyu may vary in intensity or even nature due to different distribution of Q₁ and Q₂.