Thanks for submitting this again - at 320 words, it’s much shorter than before. You have left out new information in the conclusion (good - never have new information in your conclusion!), and you've removed some other unnecessary detail throughout. The result is a clearer and stronger essay.
There are still some unnecessary details ("the USA," "outer space" – many countries are involved with space exploration., but why give special attention to this outlay instead of say, military expenditure or the billions spent on petfood?)
The one thing that stands out now is the repetition of the phrase “dying hungry” (perhaps it should be “leaving them to die hungry” or “dying of hunger”) in Paras 1, 3 and 5. Repetition can be effective, especially in speech, but in an IELTS writing essay you only have 250 words and 40 minutes to impress an examiner with your vocabulary and your ideas. Avoid repetition: it is one of the criteria for Bands 4 and 5. See the IELTS Public Writing Descriptors here.
You wrote at the start of Para 3:
The above three items are the main factors which is more than sufficient for any country to become poor and suffers from starvation.
What are these three items? I am not too sure what they are – colonization, exploitation of resources and …? However, more importantly is that good writing should go forward, not backward. Don’t make the reader jump around – keep going forward!
For example this would be a very bad sentence:
Below I will describe the three factors mentioned above, examples of which can be found in Africa, Asia and South America respectively, and more details of which can be found in the Appendix, before I return to the topic mentioned in my second paragraph and to which I return in my closing argument.
What you could do is move your sentence to the end of the previous paragraph, to act as a summary sentence.
First of all, poor countries mostly are mostly located in Africa,which had been suffered from occupation for several decades. The occupying countries had depleted them from their natural resources as minerals, petroleum oil, and agricultural crops,leaving them poor and uneducated, suffering from illiteracy, and with an inadequate healthcare system. As a result, so many epidemic diseases were widespread. These three items - colonization, exploitation, and poor health care – are the main factors contributing to poverty.
One vocab point in paragraph four: use “teach”, not “learn”