For many years, precision investment casting foundries have periodically reported serious casting defects. One source is associated with the brittle ceramic shell mould which is very weak in tension and highly expose to the cracking mechanism. This situation not only lead to the appearance of defect in the end cast product but always attribute to the handling problem at the earlier stage in the investment casting industry. Due to this fact the strengthening mechanism of the brittle shell mold using reinforcement method was studied and investigated in this work. Rice husk was chosen as a reinforcement material as it contains silica element which can withstand high temperature of molten metal. Several testing procedures and characterization technique were carried out in order to measure the performance of the reinforced shell mould. Results show that the MOR value for the green reinforced shell mould is higher than the green body of non reinforced shell mould. Scanning electron microscope observations also show that the fiber alignment across the matrix structure increase the failure resistance and yet increase the strength of the shell mould green body. Furthermore, this reinforcement method using organic fiber leads to the pore enhancement and also leads to the new phase formation (zircon) in the fired reinforced body. Overall, this reinforcement method using rice husk increase the properties of the green and fired body of ceramic shell mould system.