Effects of pure inorganic fertilizer and different amounts of compound of organic fertilizer (yard manure) and inorganic fertilization on numbers of soil microbe, soil enzyme activities, soil respiration rate and yield of peanut were studied under field condition. The results were as follows: (1) Numbers of bacteria, actinomycetes and fungi were raised with the increase of amount combined application of organic and inorganic fertilizer. Pure inorganic fertilizer had not obviously effect on the number of soil microbe.Numbers of the three kind microorganism were increased by 114.9%、49.0% and 29.0%,respectively,in medium level of combined application of organic and inorganic fertilizer compared to medium level of pure inorganic fertilizer.(2) Fertilization can significantly enhance the enzyme activity of urease, invertase, phosphatase and catalase and soil respiration rate. Enzyme activity and soil respiration rate of medium and high level of combined application were much higher than that of the other treatments. The effect of pure inorganic fertilizer with medium level was near to,or lower in late growing stage, than that of low level of combined application. Fertilization had little effects on the activity of catalase than that of the other three enzymes. (3) Significant correlative relationships were found among soil microorganisms, soil enzyme activities and soil respiration. (4) Pod yields of peanut with medium and high level of combined application were much higher than that of other treatments, and increased by 14.0% in medium level of combined application compared to in pure medium level of inorganic fertilizer(normal rate for farmer land). So, the role of organic fertilizer to yield increase through improving soil fertility was far greater than that of its direct nourishment supply in sandy soil. (5)Taking into account both soil fertility and yield of peanut, medium level of combined application of organic and inorganic fertilizer was appropriate in middle-fertility sandy soil.