Thank very much for your reply!
It seems that It is safe to ground earth symbol of below "LED" and earth symbol of below "Black probe to annode" to ground(earth) pin of AC inlet socket in the schematic.Because negative leg of "LED" and "Black probe to annode" are directly connected to negative terminal(negative DCV) of bridged rectified.So below earth symbol in orange circle is actually the same type of negative DCV terminal.
But, It is not possible and rather dangerous to ground together any terminal,which is directly connected to negative terminal(negative DCV) of bridged rectified, and any terminal, which is directly connected to terminal of the transformer secondary such as AC terminal of rectifier diode, to ground(earth) pin of AC inlet socket.because they aren't the same voltage type.