Is "not going to doctor because of fear of illness" a psychological disorder? Some people don't like to go to the doctor because they are afraid of being diagnosed sick in medical examinations or being diagnosed exacerbated when they have an illness even they know if they don't treat the illness it will get worse. 

A really large population of these kind of people exists, especially in Asia.

Is it a subtype of hypochondria? Or it is another psychological abnormality or even is normal?
What you are describing is most likely avoidance, which in itself isn't a disorder. 

People are most likely afraid of the illness in itself, and so not going to the doctor means that they don't have to confront the possibility of having that illness. This avoidance is a mechanism that maintains hypochondria or health anxiety (however you wish to call it) by negative reinforcement: 'I don't go to the doctor, I'm not told if I'm sick or not, so I'm less anxious'. 

The reduction in fear or anxiety is usually short lived and only makes it worst over time. This coping mechanism is not adaptive, and may aggravate health anxiety, but in itself, is not a disorder. 

Sources
- David Veale's website
- Centre for Clinical Interventions
- Psychology Today