Safety lift cord assembly for window blinds

A safety lift cord assembly for a window blind, comprising:

• a ladder unit including two ladder strings and multiple transverse strings which are located between the two ladder strings, the two ladder strings being parallel to each other, the transverse strings adapted to control angular status of slats of a window blind;
• two sleeves made of flexible material and located on two ends of the ladder unit, two lift cords respectively extending through the two sleeves, a first end of each lift cord adapted to be fixed to a bottom rail of the window blind, a second end of each lift cord adapted to be connected to a roller located in a top rail of the window blind, two ropes respectively extending through the two sleeves, and
• multiple retainers formed between the ladder strings and the ropes, when the lift cords are lifted, the ropes drive the ladder unit and the sleeves are collected, the retainers do not drag the sleeves.