Studies of the effects of three-dimensional (3D) propagations on MIMO channel correlation and capacity have been presented in some literatures based on given 3D stochastic models of angle spectrum. However, it is only for narrowband MIMO channels and can not properly include specular reflections due to walls and/or the ground. In this letter, a hybrid spatial channel model, which combines a 3D ray-tracing based model for deterministic rays with a new 3D model for singlebounce randomly scattering rays, is proposed to investigate wideband spatial/polarized MIMO channel correlation. Based on the proposed model, the per-tap correlation among MIMO subchannels is formulated and is validated by indoor measurements. From the comparison between measured and computed subchannel correlations, it is found that our 3D model is more accurate than the 2D model, which only considers the propagation path in the horizontal plane, for both the copolarized and the cross-polarized antenna cases. It is noted that the concept of effective scattering region is introduced in our model, which can increase computation efficiency without sacrifice the prediction accuracy.