Single-pipe ring-type mixing water oil-gathering process is often used in the oil-gas gathering and transportation system of low permeability oilfield. In order to improve the economic benefits of exploitation and construction of low permeability oilfield, multi-objective parameters optimization mathematical model of single-pipe ring-type mixing water oil-gathering process is built with the targets of minimization of pipeline construction investment, thermal energy and power energy consumption. The model belongs to the mixed-discrete variable nonlinear optimization problem. According to the structure characteristics of the model, multi-objective parameters optimization mathematical model is changed into the single-objective optimization by using linear weighting method. Then the single-objective optimization is solved by hybrid genetic algorithm. Network optimized design of a block of oil-gas gathering and transportation system is conducted by the model mentioned in this paper, and the result is that pipeline construction investment reduces 12.4 percent, thermal energy consumption reduces 14.4 percent and power energy consumption reduces 12.4 percent.