An experiment using fresh bagasse, was conducted to study the formula of matrix in tobacco float seedling production. The results showed that with compound fertilizer and calcium magnesium phosphate, bagasse could be thoroughly decomposed,，and the carbon- nitrogen ratio declined from 182.35 to 26.58 in 7 months. It was desirable for tobacco seedlings to grow in the matrix of 65% decomposed bagasse + 25% expanded perlite +10% coal silt.