If ethernet frame is transferred over serial port(COM port), wireshark can decode that frame?
If you take the contents of the Ethernet frames and arrange that they be put into a pcap file with a link-layer header type of LINKTYPE_ETHERNET (1), or a pcapng file with an interface description block with a type of LINKTYPE_ETHERNET, then Wireshark should be able to read those files and decode the Ethernet frames.
Note that they will have to be Ethernet frames - i.e., they'll need to start with a 6-octet destination MAC address, followed by a 6-octet source MAC address, followed by a 2-octet type/length field, followed by the payload. If, for example, you're sending IP packets - e.g., if you have a device that receives IP-over-Ethernet frames and sends the IP packets on the serial line, and receives IP packets over the serial lines and sends them on the Ethernet - then you'd need a different LINKTYPE_ value, such as LINKTYPE_RAW for raw IP.
Using Ethernet over a serial link seems mutually exclusive. Can you provide more information? Ethernet frames run on Ethernet links and Serial links use their own framing. Are you tunnelling?
Yes, it is mutually exclusive. We are trying to send Ethernet frame( which is normally working on Ethernet link) via Serial port instead of Ethernet link. It's a kind of tunneling. If you have any further question, feel free to ask.