We present the analyses of the stellar contents associated with the extended H ii region Sh2-252 using deep optical UBVRI photometry , slit and slitless spectroscopy along with the near-infrared ( NIR ) data from 2MASS for an area \sim 1 degree \times 1 degree . We have studied the sub-regions of Sh2-252 which includes four compact-H ii ( CH ii ) regions , namely A , B , C and E and two clusters NGC 2175s and Teutsch 136 ( Teu 136 ) . Of the fifteen spectroscopically observed bright stars , eight have been identified as massive members of spectral class earlier than B3 . From the spectro-photometric analyses , we derived the average distance of the region as 2.4 \pm 0.2 kpc and the reddening E ( B - V ) of the massive members is found to vary between 0.35 to 2.1 mag . We found that NGC 2175s and Teu 136 , located towards the eastern edge of the complex are the sub-clusters of Sh2-252 . The stellar surface density distribution in K -band shows clustering associated with the regions A , C , E , NGC 2175s and Teu 136 . We have also identified the candidate ionizing sources of the CH ii regions . 61 H \alpha emission sources are identified using slitless spectroscopy . The distribution of the H \alpha emission sources and candidate young stellar objects ( YSOs ) with IR excess on the V / ( V - I ) colour magnitude diagram ( CMD ) shows that a majority of them have approximate ages between 0.1 - 5 Myr and masses in the range of 0.3 - 2.5 M _ { \odot } . The optical CMDs of the candidate pre-main sequence ( PMS ) sources in the individual regions also show an age spread of 0.1 - 5 Myr for each of them . We calculated the K -band luminosity functions ( KLFs ) for the sub-regions A , C , E , NGC 2175s and Teu 136 . Within errors , the KLFs for all the sub-regions are found to be similar and comparable to that of young clusters of age < 5 Myr . We also estimated the mass functions ( MFs ) of the PMS sample of the individual regions in the mass range of 0.3 - 2.5 M _ { \odot } . In general , the slopes of the MFs of all the sub-regions are found comparable to the Salpeter value .