Is there any way for a ranger to have full level for animal companion?

[cerberuspuppy]

If so what is it? Feat, trait or item? What book is it in? Thanks.

[Cap. Darling]

Boon companion feat from animal archives i think it is

[Duiker]

The feat is called Boon Companion, it's in the Animal Archive and is legal for PFS in case that's also a concern.

[Rosc]

http://www.d20pfsrd.com/feats/general-feats/boon-companion
Boon Companion

Also consider the Magical Lineage trait. It adds a +2 to your caster level, up to a max of your character level this helps offset the effective -3 to CL that Rangers have when their spells kick in

[Murdock Mudeater]

Half orcs have a "beast rider" feat which adds +2 to the level and adds access to a few more mount types. Orcs can take it too, as could humans with racial heritage.

[Lakesidefantasy]

The Falconer archetype gets a full animal companion with the caveat that it has half hit points till level 4.

[The Shaman]

The Beastmaster archetype eventually gets full animal companion progression, too. I still think Boon Companion is the best option, though.