The utility model discloses a furred ceiling conversion layer is with prolonging formula triangle cat ladder device certainly, include integrative cat ladder that sets up and the fixed part that links to each other bottom the cat ladder, the upper portion of girder steel is located on the upper portion of cat ladder, and the cat ladder passes through card strip no. 1 and last girder steel fixed connection, and the fixed part passes through U type card strip and C type purlin fixed connection. The beneficial effect of the utility model: the utility model discloses triangle cat ladder device has been solved the furred ceiling dress and has been traded the problem of setting up scaffold and ground construction conflict in the construction of layer, and the construction cycle is reduced has improved the efficiency of construction.