Making a dotted line in Illustrator is easy—you just change it in the stroke palette. Photoshop, on the other hand, is a bit trickier. There is more than one way, but I want to show you how to quickly make a dotted line in Photoshop.
If you've ever made a Photoshop mock-up of a website before getting your hands dirty with code, this little trick may come in handy.
1. Open your Brushes Palette
Yep, you are going to be using a brush for this quick trick. Open your brushes palette by going to Window > Brushes, or hit F5 on your keyboard. Once open, click on “Brush Tip Shape” within the Brushes palette and select a very small brush like 1-5px.
2. Uncheck Shape Dynamics and Smoothing
3. Adjust the “Spacing” to create the dots
This part is up to you and depends on your desired effect. Pay no attention to the waves in the preview. It's the default preview. All you need to be worried about here is the amount of space between the dots.
4. Choose your brush color
If you haven't already, choose the brush tool in the tools palette, or hit B on the keyboard. Also, make sure you select a color for your brush, which would be the foreground color. ( I chose black. )
5. Hold Shift and Drag
With the brush tool, hold shift, drag and bam, perfect dotted line!