A blind assembly comprising: a first side seat; a second side seat that is spaced apart from said first side seat; a winding shaft that has an end mounted rotatably to said second side seat, and that is formed with an internal passage; a shade member that is wound on said winding shaft; and a winding device that has a fixing unit having a fixing portion that is non-rotatably disposed on said first side seat, and a spring-mounting portion that extends in a direction opposite to said fixing portion; a coupling barrel disposed in said internal passage, co-rotatable with said winding shaft, rotatable relative to said fixing unit, and having a barrel wall that defines a receiving space receiving said spring-mounting portion; and a scroll spring disposed in said coupling barrel and having a fixing end that is disposed on said spring-mounting portion, and a connecting end that is disposed on said barrel wall of said coupling barrel, such that rotation of said coupling barrel relative to said fixing unit generates a resilient force of said scroll spring for retracting said shade member, characterized in that: said barrel wall of said coupling barrel of said winding device has at least one first pin hole; said fixing unit further has a second pin hole being registered with said at least one first pin hole when said coupling barrel is rotated relative to said fixing unit until the resilient force of said scroll spring is generated; and said winding device further has a pin being insertable into one of said at least one first pin hole and said second pin hole upon registration of said at least one first pin hole with said second pin hole and generation of the resilient force, thereby maintaining the resilient force. a first side seat; a second side seat that is spaced apart from said first side seat; a winding shaft that has an end mounted rotatably to said second side seat, and that is formed with an internal passage; a shade member that is wound on said winding shaft; and a winding device that has a fixing unit having a fixing portion that is non-rotatably disposed on said first side seat, and a spring-mounting portion that extends in a direction opposite to said fixing portion; a coupling barrel disposed in said internal passage, co-rotatable with said winding shaft, rotatable relative to said fixing unit, and having a barrel wall that defines a receiving space receiving said spring-mounting portion; and a scroll spring disposed in said coupling barrel and having a fixing end that is disposed on said spring-mounting portion, and a connecting end that is disposed on said barrel wall of said coupling barrel, such that rotation of said coupling barrel relative to said fixing unit generates a resilient force of said scroll spring for retracting said shade member, a fixing unit having a fixing portion that is non-rotatably disposed on said first side seat, and a spring-mounting portion that extends in a direction opposite to said fixing portion; a coupling barrel disposed in said internal passage, co-rotatable with said winding shaft, rotatable relative to said fixing unit, and having a barrel wall that defines a receiving space receiving said spring-mounting portion; and a fixing portion that is non-rotatably disposed on said first side seat, and a spring-mounting portion that extends in a direction opposite to said fixing portion; a coupling barrel disposed in said internal passage, co-rotatable with said winding shaft, rotatable relative to said fixing unit, and having a barrel wall that defines a receiving space receiving said spring-mounting portion; and a scroll spring disposed in said coupling barrel and having a fixing end that is disposed on said spring-mounting portion, and a connecting end that is disposed on said barrel wall of said coupling barrel, such that rotation of said coupling barrel relative to said fixing unit generates a resilient force of said scroll spring for retracting said shade member, a fixing end that is disposed on said spring-mounting portion, and a connecting end that is disposed on said barrel wall of said coupling barrel, such that rotation of said coupling barrel relative to said fixing unit generates a resilient force of said scroll spring for retracting said shade member, characterized in that: said barrel wall of said coupling barrel of said winding device has at least one first pin hole; said fixing unit further has a second pin hole being registered with said at least one first pin hole when said coupling barrel is rotated relative to said fixing unit until the resilient force of said scroll spring is generated; and said winding device further has a pin being insertable into one of said at least one first pin hole and said second pin hole upon registration of said at least one first pin hole with said second pin hole and generation of the resilient force, thereby maintaining the resilient force. said barrel wall of said coupling barrel of said winding device has at least one first pin hole; said fixing unit further has a second pin hole being registered with said at least one first pin hole when said coupling barrel is rotated relative to said fixing unit until the resilient force of said scroll spring is generated; and said winding device further has a pin being insertable into one of said at least one first pin hole and said second pin hole upon registration of said at least one first pin hole with said second pin hole and generation of the resilient force, thereby maintaining the resilient force.