From the good isolation results of Negative-Stiffness (NS) suspension and Three-Parallel (TP) suspension, the new isolation models designed by NSTP suspension (combination of NS and TP) and TPNS suspension (combination of TP and NS) to improve the operator’s shaking and riding quality have been investigated based on a 3-D dynamic model of car. Sensitivity of initial parameters in NSTP and TPNS suspension are analyzed and optimised via root mean square of the vertical acceleration ( a wzs), pitching acceleration ( a wϕs), and rolling acceleration ( a wθs) of operator’s seat. Research shows that (1) the vertical-riding quality in operator’s seat designed by NSTP and TPNS suspension is enhanced by 54.9% and 55.5% compared to the traditional suspension of operator’s seat; (2) the isolation efficiency in the vertical direction of both NSTP and TPNS suspension is similar. However, the a wϕs and a wθs with TPNS suspension are greatly deteriorated by 48.9% and 54.5% in comparison with NSTP suspension; (3) design parameters of NSTP suspension greatly affect the a wzs, a wϕs, and a wθs; whereas design parameters of TPNS suspension insignificantly affect the a wzs, a wϕs, and a wθs; and (4) the a wzs, a wϕs, and a wθs with optimised TPNS suspension are smaller than designed TPNS suspension by 42.8%, 71.3%, and 78.1%, respectively. Therefore, optimised TPNS suspension should be applied to further ameliorate operator’s shaking and riding quality.