The invention provides a self-heat insulation aerated concrete building block and mortar for construction of building blocks, and relates to the field of building walls. The building block is prepared by the following components in parts by weight: 60-110 parts of a siliceous material and 25-65 parts of a calcareous material which are used as main materials, 2-6 parts of vitreous beads, 5-30 parts of an additive, 0.07-0.2 parts of a foaming agent, 1-10 parts of a foaming conditioning agent, 0.08-0.2 parts of a foam stabilizer, and water. The building block has the advantages of fire prevention, flame retardation, good mechanical strength, low heat conduction coefficient, and good thermal insulation performance. The mortar is mixed from the following components in percentages by weight: 15-45% of Portland cement, 10-30% of coarse sand, 30-50% of fine sand, 0.05-0.15% of PP fiber, 0.02-0.07% of methyl 2-hydroxyethyl cellulose, 3-5% of heavy calcium powder, 3-8% of coal ash, 0.5-1.5% of rubber powder, and water. The mortar has a high hardening volume density, so that generation of wall cracks and mortar joints is prevented, and thermal insulation performance of the wall is guaranteed.