Multi-input multi-output random vibration with six degrees of freedom control is an advanced environment test scheme. This work investigates the influence of normal acceleration on the calculation of six degrees of freedom acceleration responses in random vibration control tests. The problem is formulated first with the assumption that the shaker table is rigid and the vibration rotation is very small. A six degrees of freedom vibration system is modelled with twelve exciters and one rigid platform. Subsequently, the calculation method for multiple degrees of freedom acceleration responses considering the normal accelerations is presented. The comparison results indicate that the influence of the normal acceleration on the calculation of the six degrees of freedom responses is so small that it can be ignored. Therefore, in most cases, the six degrees of freedom accelerations of the rigid shaker table can be obtained directly from the coordinate matrix and measured linear acceleration responses.