1. A pair of pants comprising: a main body including a first piece and a second piece, the first piece and the second piece being sewn together with each other to constitute a waist wearing-portion and two leg wearing-portions, wherein a user's leg enters the leg-wearing portions through the waist-wearing portion along a wearing direction; and an auxiliary supportive-crotch including a first connecting end (200E1) and a second connecting end (200E2), characterized in that, the auxiliary supportive-crotch being sewn inside the main body the first connecting end (200E1) being connected to a first connecting region located in the inner upper edge of the first piece, and the second connecting end (200E2) being connected to a second connecting region located in the second piece, and the second connecting region of the second piece is located at the end edge (120E1) of the second piece, which is sewn together with the second connecting end (200E2) of the auxiliary supportive-crotch and the end edge (110E1) of the first piece; wherein the distance from the second connecting region to the upper edge of the first piece along the surface of the main body is a first distance, the distance from the second connecting region to the upper edge of the second piece along the surface of the main body is a second distance, and the first distance is longer than the second distance; wherein when the main body is in a folded status, the distance from the bottom edge of the first piece to the waist-wearing portion in the wearing direction is a first length, the distance from the bottom edge of the second piece to the waist-wearing portion in the wearing direction is a second length, and the distance from the second connecting region to the waist-wearing portion in the wearing direction is a third length, and when the main body expands from the folded status to a wearing status along an expanding direction, the distance from the bottom edge of the first piece to the waist-wearing portion in the wearing direction is a fourth length, the distance from the bottom edge of the second piece to the waist-wearing portion in the wearing direction is a fifth length, and the distance from the second connecting region to the waist-wearing portion in the wearing direction is a sixth length; wherein the first length is greater than the third length, and the fourth length is greater than or equal to the sixth length; wherein the wearing direction is substantially perpendicular to the expanding direction. a main body including a first piece and a second piece, the first piece and the second piece being sewn together with each other to constitute a waist wearing-portion and two leg wearing-portions, wherein a user's leg enters the leg-wearing portions through the waist-wearing portion along a wearing direction; and an auxiliary supportive-crotch including a first connecting end (200E1) and a second connecting end (200E2), characterized in that, the auxiliary supportive-crotch being sewn inside the main body the first connecting end (200E1) being connected to a first connecting region located in the inner upper edge of the first piece, and the second connecting end (200E2) being connected to a second connecting region located in the second piece, and the second connecting region of the second piece is located at the end edge (120E1) of the second piece, which is sewn together with the second connecting end (200E2) of the auxiliary supportive-crotch and the end edge (110E1) of the first piece; wherein the distance from the second connecting region to the upper edge of the first piece along the surface of the main body is a first distance, the distance from the second connecting region to the upper edge of the second piece along the surface of the main body is a second distance, and the first distance is longer than the second distance; wherein when the main body is in a folded status, the distance from the bottom edge of the first piece to the waist-wearing portion in the wearing direction is a first length, the distance from the bottom edge of the second piece to the waist-wearing portion in the wearing direction is a second length, and the distance from the second connecting region to the waist-wearing portion in the wearing direction is a third length, and when the main body expands from the folded status to a wearing status along an expanding direction, the distance from the bottom edge of the first piece to the waist-wearing portion in the wearing direction is a fourth length, the distance from the bottom edge of the second piece to the waist-wearing portion in the wearing direction is a fifth length, and the distance from the second connecting region to the waist-wearing portion in the wearing direction is a sixth length; wherein the first length is greater than the third length, and the fourth length is greater than or equal to the sixth length;