The invention discloses a convenient post-cast strip supporting device and a construction method thereof. The supporting device comprises a supporting device body connected to a position below a bottom mold of a post-cast strip, the supporting device body comprises a supporting base, an adjustable part which is connected to the top of the supporting base and a supporting top support which is connected to the adjustable part, and the top of the supporting top support is connected to the lower portion of the bottom mold of the post-cast strip. According to the convenient post-cast strip supporting device and the construction method thereof, through the arrangement of the supporting device body, a large number of supports can be saved, and most space can be reserved; fine adjustment can be carried out on on-site height through the adjustable part, and the adaptive supporting height is facilitated; through the arrangement of standard knots, threading knots and sleeve rods, batch productionof the supporting device can be carried out, and transportation and field installation are facilitated; through the arrangement of connecting joints, connecting rods can be conveniently fixed to guarantee the integrity of the supporting device, and accurate installation and further limiting are facilitated; through the arrangement of standard knot inserting holes and supporting rods, the mountingpositions of the connecting knots can be adjusted, and supporting can be carried out on the vertical directions of the connecting joints; and through the arrangement a base plate, the integrity can be enhanced.