A method for interleaving processing in a Wireless Local Area Networks, WLAN, system, characterized that the method comprises: obtaining (301, 402, 501), by a WLAN device, a predetermined number of identifiers of valid positions from any sub-interleaving processing of at least two sub-interleaving processing contained in an interleaving processing, wherein the valid positions are input/output positions of said any sub-interleaving processing and are used for transmitting data bits to be transmitted, and the number of the valid positions is less than the number of all input/output positions of said any sub-interleaving processing; determining (302, 403, 502) valid input positions of the interleaving processing according to the identifiers of the valid positions; transmitting (303, 404, 503) the data bits to be transmitted in the valid input positions, and transmitting bit 0 and/or bit 1 or no data bit in other non-valid input positions of the interleaving processing other than the valid input positions; modulating (304, 405, 504) data bits transmitted in output positions of the interleaving processing to obtain modulation signals and mapping the modulation signals onto corresponding data sub-carriers respectively, wherein the method further comprises: determining a predetermined number of positions of valid data sub-carriers used for transmitting the data bits to be transmitted according to a predetermined rule, wherein said obtaining a predetermined number of identifiers of valid positions from any sub-interleaving processing contained in the interleaving processing comprising: randomly obtaining the predetermined number of the identifiers of the valid positions from any sub-interleaving processing contained in the interleaving processing according to the predetermined number of positions of the valid data sub-carriers determined and determining valid output positions of the interleaving processing according to the identifiers of the valid positions wherein said mapping the modulation signals onto the corresponding data sub-carriers respectively comprises: mapping the modulation signals corresponding to the data bits carried in the valid output positions onto the corresponding data sub-carriers respectively through mapping processing of the data sub-carriers. obtaining (301, 402, 501), by a WLAN device, a predetermined number of identifiers of valid positions from any sub-interleaving processing of at least two sub-interleaving processing contained in an interleaving processing, wherein the valid positions are input/output positions of said any sub-interleaving processing and are used for transmitting data bits to be transmitted, and the number of the valid positions is less than the number of all input/output positions of said any sub-interleaving processing; determining (302, 403, 502) valid input positions of the interleaving processing according to the identifiers of the valid positions; transmitting (303, 404, 503) the data bits to be transmitted in the valid input positions, and transmitting bit 0 and/or bit 1 or no data bit in other non-valid input positions of the interleaving processing other than the valid input positions; modulating (304, 405, 504) data bits transmitted in output positions of the interleaving processing to obtain modulation signals and mapping the modulation signals onto corresponding data sub-carriers respectively, wherein the method further comprises: determining a predetermined number of positions of valid data sub-carriers used for transmitting the data bits to be transmitted according to a predetermined rule, determining a predetermined number of positions of valid data sub-carriers used for transmitting the data bits to be transmitted according to a predetermined rule, wherein said obtaining a predetermined number of identifiers of valid positions from any sub-interleaving processing contained in the interleaving processing comprising: randomly obtaining the predetermined number of the identifiers of the valid positions from any sub-interleaving processing contained in the interleaving processing according to the predetermined number of positions of the valid data sub-carriers determined and determining valid output positions of the interleaving processing according to the identifiers of the valid positions randomly obtaining the predetermined number of the identifiers of the valid positions from any sub-interleaving processing contained in the interleaving processing according to the predetermined number of positions of the valid data sub-carriers determined and determining valid output positions of the interleaving processing according to the identifiers of the valid positions wherein said mapping the modulation signals onto the corresponding data sub-carriers respectively comprises: mapping the modulation signals corresponding to the data bits carried in the valid output positions onto the corresponding data sub-carriers respectively through mapping processing of the data sub-carriers. mapping the modulation signals corresponding to the data bits carried in the valid output positions onto the corresponding data sub-carriers respectively through mapping processing of the data sub-carriers.