The invention relates to environment-friendly chlorine-free drilling fluid, which is characterized in that the environment-friendly chlorine-free drilling fluid is prepared from the following components in percentages by weight: 8 to 18 percent of chlorine-free strongly inhibitory compound salt; 0.2 to 0.3 percent of drilling fluid tackifier; 1.5 to 3 percent of water-dispersible cationic emulsified asphalt powder; 0.2 to 0.4 percent of salt-resistant and calcium-resistant filtrate reducer; 0.2 to 0.5 percent of natural polymer filtrate reducer; 2 to 4 percent of acid-soluble temporarily plugged reservoir protection agent; 0.1 percent of caustic soda; and the balance of clean water. The environment-friendly, chlorine-free, low-density, low-solid phase, strong-chemical inhibition and anti-collapse drilling fluid can inhibit the collapse of mudstone sections under the condition of low density, and meets the friction drag reduction of long open hole sections with low solid phase.