How is Orwell's attitude toward his job ambivalent?

To be ambivalent about something is to have conflicted or mixed emotions about it. A person who is ambivalent lacks conviction in one direction or the other; they are in two minds about whatever the issue is. Orwell, in this story, is definitely ambivalent toward his job. He is not a passionate defender of the British Empire; his experiences in Burma have led him to conclude that imperialism is "evil," and he is inclined to feel that the sooner he has "chucked" his job, the better. This is not a man experiencing high levels of job satisfaction, and, in theoretical terms, he takes the side of the Burmese against their British oppressors. However, in reality, he finds his situation very "perplexing." Anti-British feeling runs very high in Burma and, as a sub-divisional police officer responsible for implementing the regime, Orwell finds himself the target of this hatred. This is confusing for him because he has never really been hated in his life before; also, he doesn't really believe in the regime which, in the eyes of the Burmese, he represents.
He enacts his job because he has to, and because he is unsure what will happen to him if he doesn't. He has "no intention of shooting the elephant" at first, but he is only going along with what he feels he has to do.

Orwell is serving as a police officer for the British Empire in Lower Burma, and he writes that the anti-European sentiment in the country is "perplexing and upsetting." His experience makes him feel that "imperialism is an evil thing" and that he must quit his job as soon as possible. On the other hand, he is aware that he feels irrational hatred towards the people he must work with in Burma. 
When he hears that an elephant is destroying the bazaar, he approaches his task of shooting the elephant with great ambivalence. His sense of duty, weak though it is, propels him to grab his gun and go in search of the marauding elephant. Though he knows that he should not shoot the elephant, who is actually doing no harm, the crowd of people urging him on forces him to shoot the elephant to "avoid looking a fool." He feels great ambivalence in shooting the elephant because he knows it is unnecessary, and he feels great ambivalence about working for an empire that only engenders resentment in the people it attempts to control.