A tri-proof structure being a waterproof, dustproof and shockproof housing, the tri-proof structure comprising a first casing, a second casing, and a third casing, the first casing and the third casing being respectively assembled to the second casing, the tri-proof structure being characterized by: the first casing provided with a protrusion; the second casing made of soft material and defining a first groove corresponding to the protrusion of the first casing, the soft material being elastic material; the third casing provided with a convex block, the convex block being a protrusion belonging to the third casing; wherein the second casing defines a second groove corresponding to the convex block; wherein the protrusion and the first groove, and the convex block and the second groove each is interference fit, the second casing further comprises an appearance surface, the appearance surface is an external and visible peripheral surface of the second casing, the first casing and the third casing further respectively comprises an outer surface (12, 32), the appearance surface is protruded out of the outer surfaces (12, 32) of the first casing and the third casing; wherein the third casing further comprises opposite upper and lower ends (33, 34), the opposite upper and lower ends (33, 34) of the third casing employ another waterproof structure, the opposite upper and lower ends (33, 34) of the third casing respectively define a concavity, the second casing also further comprises another opposite upper and lower ends (23, 24), the another opposite upper and lower ends (23, 24) of the second casing are strip-like structures, the another opposite upper and lower ends (23, 24) of the second casing being strip-like structures are assembled in the concavities and are interference fit with the first casing to assemble together with the first casing; wherein the first casing also comprises opposite upper and lower ends structures (13, 14), the opposite upper and lower ends structures (13, 14) of the first casing are respectively provided with a protruding strip, the protruding strip is a protrusion and strip-shaped, the protruding strips of the first casing are assembled in the concavities of the third casing to be interference fit with the another opposite upper and lower ends (23, 24) of the second casing being strip-like structures in the concavities of the third casing, the protruding strips of the first casing presses the another opposite upper and lower ends (23, 24) of the second casing being strip-like structures to be elastically deformed in the concavities of the third casing. the first casing provided with a protrusion; the second casing made of soft material and defining a first groove corresponding to the protrusion of the first casing, the soft material being elastic material; the third casing provided with a convex block, the convex block being a protrusion belonging to the third casing; wherein the second casing defines a second groove corresponding to the convex block; wherein the protrusion and the first groove, and the convex block and the second groove each is interference fit, the second casing further comprises an appearance surface, the appearance surface is an external and visible peripheral surface of the second casing, the first casing and the third casing further respectively comprises an outer surface (12, 32), the appearance surface is protruded out of the outer surfaces (12, 32) of the first casing and the third casing; wherein the third casing further comprises opposite upper and lower ends (33, 34), the opposite upper and lower ends (33, 34) of the third casing employ another waterproof structure, the opposite upper and lower ends (33, 34) of the third casing respectively define a concavity, the second casing also further comprises another opposite upper and lower ends (23, 24), the another opposite upper and lower ends (23, 24) of the second casing are strip-like structures, the another opposite upper and lower ends (23, 24) of the second casing being strip-like structures are assembled in the concavities and are interference fit with the first casing to assemble together with the first casing; wherein the first casing also comprises opposite upper and lower ends structures (13, 14), the opposite upper and lower ends structures (13, 14) of the first casing are respectively provided with a protruding strip, the protruding strip is a protrusion and strip-shaped, the protruding strips of the first casing are assembled in the concavities of the third casing to be interference fit with the another opposite upper and lower ends (23, 24) of the second casing being strip-like structures in the concavities of the third casing, the protruding strips of the first casing presses the another opposite upper and lower ends (23, 24) of the second casing being strip-like structures to be elastically deformed in the concavities of the third casing.