The utility model relates to a portable construction board which comprises a first stand column and a second stand column, the first stand column and the second stand column are both U-shaped components with U-shaped grooves, and the U-shaped grooves of the first stand column and the second stand column are oppositely arranged. A first cross beam is arranged between the first stand column and thesecond stand column, and the two ends of the first cross beam extend into the U-shaped grooves of the first stand column and the second stand column respectively; a first sliding groove in the vertical direction is formed in the second stand column, one end of the first cross beam is hinged to the top end of the first stand column, the other end of the first cross beam is in sliding connection with the first sliding groove through a pin shaft to achieve relative sliding, and the first cross beam is detachably connected with the flexible plate body. A second cross beam is arranged between the first stand column and the second stand column and located below the first cross beam. The portable construction billboard can reduce the size of the construction billboard in the transportation process, is convenient to carry, and can adapt to planes with different gradients.