In　cognitive　radio　(CR)　networks,　there　is　a　common　assumption　that　the　secondary　devices　always　obey　the　spectrum　access　rules　and　are　under　full　control.　However,　this　may　become　unrealistic　for　future　CR　networks　composed　of　intelligent,　complicated　and　autonomous　devices.　To　solve　this　problem,　the　concept　of　＂proactive-optimization＂　cognitive　radio　(POCR)　is　proposed　in　this　paper,　in　which　the　highly-intelligent　secondary　users　proactively　optimize　their　own　behavior　decisions　according　to　the　available　information　including　device　state　and　network　condition　to　maximize　their　long-term　reward.　Furthermore,　we　propose　an　optimal　transmission　behavior　decision　scheme　for　secondary　users　in　POCR　networks　considering　imperfect　spectrum　channel　sensing　results.　Specifically,　we　formulate　the　system　as　a　partially-observable　Markov　decision　process　(POMDP)　problem.　With　this　formulation,　a　low　complexity　dynamic　programming　framework　is　introduced　to　obtain　the　optimal　behavior　policy.　Extensive　simulation　results　are　presented　to　illustrate　the　significant　performance　improvement　of　the　proposed　scheme　compared　with　the　existing　one　that　ignores　the　secondary　user　behavior　optimization.