Aiming at the present situation of the contradiction existing between the decoupling difficulty and configuration complexity of sixaxis accelerometer, a new design scheme of prestressed parallel sixaxis accelerometer with 12 branch chains is presented, and the decoupling algorithm in four dimensional configurationspace is constructed. By recomposing the input parallel items and solving forward dynamics equations and force coordination equations, the ingredients of the outputs are dissected. Through introducing prematrix, postmatrix and aided angular velocity, the complex dynamic equations are transformed into two simple linear ordinary differential equations, and the explicit recursive formulas of key characteristic quantities are derived using trapezoidal method. ADAMS simulation is conducted to verify the decoupling algorithm, and the relative composite error between the decoupling algorithm and ADAMS simulation is only 0.62%, and the decoupling algorithm has higher calculation efficiency. Laboratory test results show that within one minute the composite error of the real physical prototype is 8.42%, which verifies the feasibility and correctness of the proposed design scheme. Through Taylor expansion around discrete nodes, the analytic formulas of local truncation error are derived, which provides a basis for improving the decoupling accuracy. Furthermore, the decoupling algorithm is generalized to be suitable for general configuration. Through introducing two theorems concerning vector independent elements, it is proved that the least number of branch chains for the prestressed parallel sixaxis accelerometer is 7, and the least degrees of freedom for corresponding topological configuration is 6.