The scale plugging problem is one of the main problems causing the production reduction of oil and gas fields. The common acid deplugging agent is highly corrosive，which affects the safe production of oil and gas wells. In order to solve the above problems，the HOMO/LUMO level and binding energy of chelating agents with metal ions were calculated by using Gaussian 09 software to optimize the molecular structure of several chelating agents. The chelating agent diethylenetriamine pentaacetic acid（DTPA）was selected. At the same time，computational chemistry was used to explore the mechanism of the compound detergent，and the synergistic effect between different additives was studied. On the basis of theoretical research，a non-acid scale removal agent system with DTPA as the main agents was developed：12% DTPA+0.3% scale inhibitor PASP+0.4% penetrant JFC. The scale dissolution rate of the system could reach more than 80% for a certain site scale sample，exhibiting good scale dissolving effect. According to the kinetic simulation，it was verified that the dissolving process of calcium carbonate by the descaling agent system conformed to the quasi-second-order kinetic model.