The utility model relates to an automatic cigarette ash collection anti-dropping net, which is a net-shaped tube made of a representative material expending with hot and contracting with cold, is slightly wider and longer than a cigarette and can prevent cold cigarette ash form dropping. One end of the net-shaped tube is sealed, and the other end is integrally connected with a cigarette holder through a blocking groove. A lighted cigarette is inserted into the cigarette holder and then sleeved with the automatic cigarette ash collection anti-dropping net, and the heated part of the net expands to facilitate air entry for supporting combustion. Cigarette ash is in bulk state when being hot and not easily drops from the expanded net holes. The net holes expands forwards with the burning of the cigarette and, meanwhile, contracts with the cooling of the cigarette ash, so that the cigarette ash is collected in the net-shaped tube to realize dropping prevention. A smoker can pour the cigarette ash and a cigarette end into an ash tray only by screwing the blocking groove. The utility model can prevent lighted cigarette and hot cigarette ash from burning skin and clothing, cigarette end from firing others inflammable or flammable solid subjects to cause a fire, and cigarette from flying to affect sanitation.