Abstract　

Dense molecular gas and star formation have a tight relationship, but the correlation between the gas tracers with critical density higher than 10^4 cm^-3 and Star Formation Rate (SFR) is still a controversial question. The rotational transition lines of CS molecule would better trace dense gas than HCN/HCO+ for galaxies, because its emission is less contaminated. Using the IRAM 30-m, SMT 10-m, and APEX 12m telescopes, we are systematically surveying the CS 2→1/3→2/5→4/ 7→6 in about 40 local gas-rich galaxies including normal galaxies, starbursts, and (U)LIRGs. Our preliminary results of CS 2→1/3→2/5→4/7→6 surveys agree with the Galactic studies, in contradictory to theoretical predictions.