The relationship between revenue and cost is established to find the intrinsic nature with integrated Cobb-Douglas function. It is found when the best labour is 98 the cost is low and the number of cars are 1.1 with the best profit intersection of 41 thousand Yuan which is best profit point with integrated method. When the best capital is 498Yuan the profit point is 1.1 of the number of cars with the 40 thousand Yuan too. The intersection of pieces and value between profit and cost attains 0.9 and 1.16 pieces with 32 and 41 thousand Yuan at the best capital and labor respectively. This is the important one in the course of profit. It is transferring the start and end point. Generally this point is regarded the best profit begins and may be chosen as the best profit. Meantime in the scope of PAA and PAC it has 0≤Aprofit≤AC, PAC and PAR it has AC≤Aprofit≤AR and ≥PAR it has Aprofit ≥AR. So the best profit has been accessed PAR the average profit is bigger than AR ie.Aprofit ≥AR. It is the last one mentioned above if manufacturer has enough investment capital and technique workers.The Cobb-Douglass Function has been a limited for example the the precision matter that makes the modeling a certain thing.