The experiment was carried out during the months from (June – August), in 2007 at the Agricultural Researches Station, Faculty of Agriculture, MansouraUniversity. This work aimed to study the effect of cutting rice straw and the various additions on some chemical and physical properties of rice straw compost at different periods during composting(60,75and 90days). Relevant data revealed that ,the total organic carbon, total nitrogen and C/N ratio of the composted rice straw was significantly affected by cutting and different additive of urea (0, 10.13 , 15.46  and 24.54 g urea /Kg) , lime with (10g/kg  and without adding) , super phosphate 15g/Kg and clay soil (100g/kg) at the periods of composting. The pH value and  EC value of the composted rice straw was significantly affected by  cutting , different additive of  urea  and   lime  at the periods of composting .Treatment of fine rice straw (L1) gave the greatest bulk density and water holding capacity, However, the treatment of high tall rice straw (L2) gave the lower values at the three periods. In addition, relevant results suggestedcutting rice straw and addition some additives such as urea and lime to improve some chemical and physical properties of rice straw compost.