PCBs produced using EasyEDA and supplied by JLCPCB are high quality professionally manufactured boards with through plated holes, solder mask and silkscreen printing. The default number of layers for EasyEDA is 2. EasyEDA produces PCBs with pads on all layers, i.e. in the default case, on the top and bottom layers. These pads are connected to each other by plated through holes. You can choose to lay out the PCB with components on the top or the bottom or if you wish, on both sides. If you are using through hole components then you would normally lay out the PCB as viewed looking down onto the top, component side. Because the component lead holes and any vias you or the autorouter inserts to swap track sides are through plated then you have complete freedom to route on either side and still be able to solder from the bottom, component lead side only. In EasyEDA, it is less work and costs the same to have a double sided PCB as for a single sided. If you just want to produce your own single sided boards without through plated holes, no solder mask and no silkscreen then you may be able to set up the Autorouter to ignore the top layer or possibly fool it by placing a copper area all over the top layer assigned to some net that does not exist in your schematic. Or learn to do manual routing: if it's a single sided PCB with leaded components then it can't be that complicated so manual routing would be easy enough and you'd probably end up with a better layout than the Autorouter anyway. Then just select the bottom layer to print out to make your mask or whatever. You could also generate the Gerbers in the normal way and then just use the bottom layer file.

oh many thank for your soon answer... sorry for my english : ) you wrote: "If you just want to produce your own single sided boards without through plated holes, no solder mask and no silkscreen then you may be able to set up the Autorouter to ignore the top layer or possibly fool it by placing a copper area all over the top layer assigned to some net that does not exist in your schematic."  i try to make a red (or blue) copper area all over the pcb .... nothing the trouble is the same, the autorouter make blue and red line from components... i want only bottom line (for me is RED lines).. because i use this kind of component (see attachment) and i cant soldering in both layer. sorry but i have to make pcb with art work and i can use JLCPCB. only solution that i found.... is to check manually all the line to make red connection with component... but is too long to do! thank you and best regards, Frank

"... sorry but i have to make pcb with art work and i can use JLCPCB." Do you mean that yiou have to make the pcb by hand with art work because you can **not** use JLCPCB?

oh, sorry i forget "NOT" word... correct: " i have to make pcb with art work and i can not use JLCPCB." i need to make pocb by hand with an artwork, (because is a gift for a friend) i'll use JLCPCB for the next pcb....

You can tell the Autorouter to route on the bottom - or any other selectable - layer only: