The invention discloses an alkali-efflorescence-free high-waterproofness dry-powder tile joint mixture which is prepared from the following raw materials in percentage by weight: 28-35% of ordinary silicate cement, 22-35% of coal ash, 22-32% of super fine activated admixture, 3-8% of needle-shaped wollastonite powder, 3-8% of coarse whiting powder, 0.5-2% of redispersible latex powder, 0.1-0.6% of a water repellent, 0.1-0.6% of cellulose ether, 0.1-0.6% of an alkali efflorescence inhibitor, 0.1-0.5% of wood fiber and 0.1-0.3% of a defoaming agent. Due to the adopted super fine activated admixture, the alkali efflorescence phenomenon of an ordinary cement base joint mixture is effectively inhibited, and the overall decoration effect of the tile joint mixture is greatly improved. The water repellent used in the joint mixture is redispersible water repellent powder which has good peaceability with water, so that the joint mixture has a very excellent overall water repellent effect in a hardened state and is especially applicable to relatively damp places such as bathrooms and swimming pools.