A flash device access method, wherein the flash device comprises a controller and a storage array, the storage array comprises a specific storage unit and a user storage unit, the specific storage unit is configured to store specific data, the user storage unit is configured to store user data, the specific data is used to determine a decision voltage for reading the user data, and the method comprises: • reading, by the controller, the specific data stored in the specific storage unit, wherein the reading, by the controller, the specific data stored in the specific storage unit comprises: ∘ obtaining, by the controller, a current threshold voltage of the specific storage unit; and ∘ comparing, by the controller, a preset decision voltage with the current threshold voltage of the specific storage unit, to determine the specific data stored in the specific storage unit, wherein there are at least two preset decision voltages, wherein the comparing, by the controller, the preset decision voltage with the current threshold voltage of the specific storage unit, to determine the specific data stored in the specific storage unit comprises: ▪ comparing, by the controller, each preset decision voltage among the at least two preset decision voltages with the current threshold voltage of the specific storage unit, to determine the specific data stored in the specific storage unit; • determining, by the controller, a decision voltage based on the read specific data, the determining, by the controller, the decision voltage based on the read specific data comprises: ▪ comparing, by the controller, for each of the at least two preset decision voltages, the determined specific data with recorded original specific data, to obtain a bit error rate of the determined specific data; and ▪ selecting, by the controller, a preset decision voltage, among the at least two preset decision voltages, corresponding to determined specific data with a minimum bit error rate as the determined decision voltage; and • reading, by the controller by using the selected decision voltage, the user data stored in the user storage unit. • reading, by the controller, the specific data stored in the specific storage unit, wherein the reading, by the controller, the specific data stored in the specific storage unit comprises: ∘ obtaining, by the controller, a current threshold voltage of the specific storage unit; and ∘ comparing, by the controller, a preset decision voltage with the current threshold voltage of the specific storage unit, to determine the specific data stored in the specific storage unit, wherein there are at least two preset decision voltages, wherein the comparing, by the controller, the preset decision voltage with the current threshold voltage of the specific storage unit, to determine the specific data stored in the specific storage unit comprises: ▪ comparing, by the controller, each preset decision voltage among the at least two preset decision voltages with the current threshold voltage of the specific storage unit, to determine the specific data stored in the specific storage unit; ∘ obtaining, by the controller, a current threshold voltage of the specific storage unit; and ∘ comparing, by the controller, a preset decision voltage with the current threshold voltage of the specific storage unit, to determine the specific data stored in the specific storage unit, wherein there are at least two preset decision voltages, wherein the comparing, by the controller, the preset decision voltage with the current threshold voltage of the specific storage unit, to determine the specific data stored in the specific storage unit comprises: ▪ comparing, by the controller, each preset decision voltage among the at least two preset decision voltages with the current threshold voltage of the specific storage unit, to determine the specific data stored in the specific storage unit; • determining, by the controller, a decision voltage based on the read specific data, the determining, by the controller, the decision voltage based on the read specific data comprises: ▪ comparing, by the controller, for each of the at least two preset decision voltages, the determined specific data with recorded original specific data, to obtain a bit error rate of the determined specific data; and ▪ selecting, by the controller, a preset decision voltage, among the at least two preset decision voltages, corresponding to determined specific data with a minimum bit error rate as the determined decision voltage; and ▪ comparing, by the controller, for each of the at least two preset decision voltages, the determined specific data with recorded original specific data, to obtain a bit error rate of the determined specific data; and ▪ selecting, by the controller, a preset decision voltage, among the at least two preset decision voltages, corresponding to determined specific data with a minimum bit error rate as the determined decision voltage; and • reading, by the controller by using the selected decision voltage, the user data stored in the user storage unit.