The positive-parity bands in ^224−234Th are studied using the projected shell model (PSM) approach. The energy levels, deformation systematics, $B(E2)$ transition probabilities and nuclear 𝑔-factors are calculated and compared with the experimental data. The calculation reproduces the observed positive-parity yrast bands and $B(E2)$ transition probabilities. Measurement of $B(E2)$ transition probabilities for higher spins and 𝑔-factors would be a stringent test for our predictions. The results of theoretical calculations indicate that the deformation systematics in ^224−234Th isotopes depend on the occupation of low 𝑘 components of high j orbits in the valence space and the deformation producing tendency of the neutron–proton interaction operating between spin orbit partner (SOP) orbits, the $[(2g_{9/2}_{\pi}) - (2g_{7/2})_{\nu}]$ and $[(1i_{13/2})_{\pi} - (1i_{11/2})_{\nu}]$ SOP orbits in the present context. In addition, the deformation systematics also depend on the polarization of $(1h_{11/2})_{\pi}$ orbit. The low-lying states of yrast spectra are found to arise from 0-quasiparticle (qp) intrinsic states whereas the high-spin states turn out to possess composite structure.