Although chlorine is an electron-withdrawing group, yet it is ortho, para-directing in electrophilic aromatic substitution reactions. Why?

Chlorine withdraws electron through inductive effect and releases electron through resonance. Through inductive effect, chlorine destabilizes the intermediate carbocation formed during the electrophilic substitution.

Through resonance, halogen tends to stabilise the carbocation and the effect is more pronounced at ortho- and para- positions. The
inductive effect is stronger than resonance and causes net electron withdrawal and thus causes net deactivation. The resonance effect tends to oppose the inductive effect for the attack at ortho- and parapositions and hence makes the deactivation less for ortho- and paraattack.
Reactivity is thus controlled by the stronger inductive effect and orientation is controlled by resonance effect.