The invention discloses a thermal-insulation mortar. The thermal-insulation mortar comprises the following components in parts by weight: 30-40 parts of Portland cement, 20-30 parts of glazed hollow beads, 10-15 parts of thermal-insulation aggregates, 5-10 parts of anti-crack materials and 5-10 parts of functional materials. The thermal-insulation mortar has the advantages that the anti-cracking ability is excellent, and common problems that the thermal-insulation mortar is cracked, flaked and the like can be solved; the bonding strength is high, the adhesive force is strong, and the heat preservation and heat insulation properties, the weather resistance, the fire resistance, water resistance, and the frost resistance are excellent; furthermore, the volume stability of the thermal-insulation mortar is good; the thermal-insulation mortar generates volume microdilatancy during condensation and hardening and is not cracked and hollowed; the water resistance is high; the thermal-insulation mortar is aging-resistant and long in service life.