This paper studies the optimal licensing scheme for a partially privatized public innovator under information asymmetry． It is confirmed that the separating contract strictly dominates the pooling contract for any level of partial privatization． Compared to the excluding contract，the separating contract is superior and emerges as the ultimate equilibrium when the privatization ratio is low; otherwise，the excluding contract becomes the ultimate equilibrium． Given the optimal contract，the public innovator is more likely to prefer a fixed fee when the privatization ratio is relatively small，but is more likely to prefer a royalty when the privatization ratio becomes large． From the perspective of welfare，the separating contract is often associated with the highest social welfare，while the excluding contract never yields the highest social welfare．