Study the density, volume and radioactivity of outcrop samples at Khao Chaison hot spring, Songkhla lake basin. The objective of these physical properties of rocks. The results obtained from the present study the density of Permian limestone of 2,654 ± 80 kg/m3 and volume 706.48 ± 99.50 cm3. Radioactivity measurement by using a high – purity germanium (HPGe) detector and gamma spectrometry. It was found there radioactivity 238U, 232Th and 40K with average values 4.354 ± 0.025, 18.034 ± 0.481 and 235.882 ± 0.321 Bq/Kg respectively, which are lower than radioactivity limestone in Thailand.