A safety lock mounted on an umbrella stroller comprises at least a release actuator movably mounted on a pair of push bars of an umbrella baby stroller, an articulated joint mounted with the umbrella baby stroller, a latch member for locking the articulated joint, an associating member for connecting between the release actuator and the latch member, and a resilient member for keeping the latch member biased in a locked position. The umbrella baby stroller may include an upper frame, a lower frame connected to the upper frame by the articulated joint, and a spread mechanism pivotally connected between the upper frame and the lower frame. When the spread mechanism is unlocked, the safety lock shall stop any further folding in longitudinal direction, and the user can complete the full folding in longitudinal direction if only if to pull the release actuator to unlock the safe lock.