Choosing the Best Capacitor: How to Select by Voltage, Capacitance, ESR, and Type

When you know the components requirement of the design circuit , like the capacitor, you know the specific parameters of it, but it still has problem to choose the best and proper one, what would you do?

Hi HhONg-I often go to the website of my favorite distributor- usually Digi-Key, and start by just typing "capacitor" in the search field.  I am then presented with a whole bunch of options, and I start narrowing it down until I find the perfect one for my application.  This allows me to see all types of capacitors from a number of manufacturers.Other suppliers may have a lower price, and may have more items in stock, but in my opinion Digi-Key's search engine is the best.-Rick

Thanks a lot. I know the Digi-key is not bad, but what i really need is how to make a suitbale choice at a limitation.

Hi, HhONgI think you should know what you really want based on your reality. You know  when you make a design circuit diagram into the reality, the situation is more complex, because many factors will affect the performance of capacitors, such as the temperature, humidity, heat and so on, but the most important is its real application and how much you can spend on it . so I recommend you to read it: How To Select a Capacitor?. Although it is about theory, but it can give you a clear idea to make sure something to decide what you should thought before you do it.

Can you give me an example of the  circuit you are working on so I can understand your needs better?
-Rick 

There's a wide range of different capacitors you  will want for many different circuits. It helps to know the application.
I think the first step is figuring do you want through hole or surface mount? How are you connecting this to your circuit?Next is what size capacitor you need, ie how much capacitance? This dictates everything else (physical size, voltage rating, ESR, type of capacitor).Next move onto voltage rating, this is typically 2 to 2.5 times your maximum voltage that the capacitor will experience. While this is a rule of thumb, sometimes it's not always possible. Supercaps are generally rated for about 5V or less and operated up to 4V. 
Octopart have an interesting blog post on choosing a capacitor. It looks at the different types and their advantages/disadvantages: https://octopart.com/blog/archives/2016/03/how-to-select-a-capacitor
Hope that helps a little.