Abstract: In recent times, the design of gears using computer has become a highly complicated and comprehensive subject.This study therefore present a new method of how the spur gear can be designed and detailed with computer aided design, previously, emphasis was laid on primitive and probabilistic design processes which resulted in high operation cost and prolong time. A reliability model of the spur gear when designed using computer aided performed repetitive and routine tasks involved in design drawings, review and evaluation, produces accurate and efficient design drawings as a result of interactive computer graphics and provides substantial saving in time and cost of production.